V8 SpiderMonkey JavaScriptCore Chakra Carakan KJS Other
Minor difference (1 point) Small feature (2 points) Medium feature (4 points) Large feature (8 points)
Compilers/polyfills Desktop browsers Servers/runtimes Mobile
Feature name Current browser ES6
Trans-
piler
Traceur Babel 6 +
core-js 2
Babel 7 +
core-js 2
Babel 7 +
core-js 3
Closure 2019.01 Closure 2020.01 Closure 2020.01 Closure 2020.03 Closure 2020.05 Closure 2020.06 Closure 2020.09 Closure 2021.08 JSX Type-
Script +
core-js 2
Type-
Script +
core-js 2
Type-
Script +
core-js 2
Type-
Script +
core-js 3
Type-
Script +
core-js 3
Type-
Script +
core-js 3
Type-
Script +
core-js 3
Type-
Script +
core-js 3
es6-shim Konq 4.14[1] IE 10 IE 11 FF 68 ESR FF 78 ESR FF 79 FF 80 FF 81 FF 82 FF 83 FF 84 FF 85 FF 86 FF 87 FF 88 FF 89 FF 90 FF 91 ESR FF 92 FF 93 OP 12.10 CH 85 CH 86 CH 87 CH 88 CH 89 CH 90 CH 91 CH 92 CH 93 CH 94 Edge 18 Edge 83 Edge 84 Edge 85 Edge 86 Edge 87 Edge 88 Edge 89 Edge 90 SF 12.1 SF 13 SF 13.1 SF 14 SF 14.1 SF 15 SF TP WK OP 69 OP 70 OP 71 OP 72 OP 73 OP 74 OP 75 OP 76 Rhino 1.7.13 PJS Echo JS XS6 JXA Node 0.10[2] Node 0.12[3] Node 4[3] Node >=6.5 <7[3] Node 7.0-7.5[3] Node >=7.6 <8[3] Node >=8.0 <8.3[3] Node >=8.3 <8.7[3] Node >=8.7 <8.10[3] Node >=8.10 <9[3] Node >=10.0 <10.4[3] Node >=10.4 <10.9[3] Node >=10.9 <11[3] Node 11[3] Node 12.0-12.4[3] Node 12.5-12.8[3] Node 12.9-12.10[3] Node >=12.11 <13[3] Node 13.0-13.1[3] Node >=13.2 <14[3] Node >=14.0 <14.5[3] Node >=14.5 <14.6[3] Node >=14.6 <15[3] Node >=15.0 <16[3] Node 16+[3] DUK 1.5 DUK 1.6 DUK 1.7 DUK 1.8 DUK 2.0 DUK 2.1 DUK 2.2 DUK 2.3 JrS 1.0 JrS 2.0 JrS 2.1.0 JrS 2.2.0 JrS 2.3.0 JrS 2.4.0 JJS 1.8 JJS 9 JJS 10 GraalVM 19.3.1[4] GraalVM 19.3.6[4] GraalVM 20.0.0[4] GraalVM 20.1.0[4] GraalVM 20.3.0[4] GraalVM 20.3.1[4] GraalVM 21.0.0[4] Hermes 0.7.0 AN 4.4 AN 4.4.3 iOS >=10.3 <11 iOS 11 iOS 11.3 iOS 12 iOS 12.2 iOS 13 iOS 13.4 iOS 14 iOS 15 Samsung 12 Samsung 13 Samsung 14 Samsung 15 Opera Mobile 57 Opera Mobile 58 Opera Mobile 59 Opera Mobile 60 Opera Mobile 61 Opera Mobile 62 Opera Mobile 63
Optimisation
§proper tail calls (tail call optimisation) 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 0/2 0/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 1/2 1/2 1/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 2/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2 0/2
§direct recursion ? Flag[5] No No No ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No Yes ? ? Yes ? ? ? ? Flag[7] Flag[7] Flag[7] No[8] No[8] No No No No No No No No No No No No No No No No No ? ? ? ? Yes Yes Yes Yes ? No No No No No ? ? ? No No No No No No No No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No
§mutual recursion ? Flag[5] ? ? ? ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No Yes ? ? Yes ? ? ? ? Flag[7] Flag[7] Flag[7] No[8] No[8] No No No No No No No No No No No No No No No No No ? ? ? ? No No No Yes ? No No No No No ? ? ? No No No No No No No No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes No No No No No No No No No No No
Syntax
§default function parameters MDN (Mozilla Development Network) logo  4/7 4/7 4/7 4/7 4/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 0/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 4/7 7/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 4/7 4/7 6/7 7/7 7/7 0/7 4/7 4/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 5/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7
§basic functionality Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§explicit undefined defers to the default Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§defaults can refer to previous params Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§arguments object interaction Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§temporal dead zone ? ? No No No Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No No Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§separate scope ? ? No No No Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§new Function() support ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? No[0] Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§rest parameters MDN (Mozilla Development Network) logo  2/5 4/5 3/5 3/5 3/5 2/5 2/5 2/5 2/5 2/5 2/5 2/5 2/5 3/5 4/5 4/5 4/5 4/5 4/5 4/5 4/5 4/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 3/5 5/5 0/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 0/5 3/5 3/5 5/5 5/5 5/5 0/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 4/5 0/5 0/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5 5/5
§basic functionality Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§function 'length' property Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§arguments object interaction ? Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§can't be used in setters ? Yes No No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§new Function() support ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? No[0] Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§spread syntax for iterable objects MDN (Mozilla Development Network) logo  8/15 15/15 13/15 13/15 14/15 11/15 11/15 11/15 11/15 11/15 11/15 11/15 11/15 2/15 14/15 14/15 14/15 14/15 14/15 14/15 14/15 14/15 0/15 0/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 10/15 15/15 11/15 0/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 0/15 15/15 15/15 15/15 0/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 0/15 0/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15 15/15
§with arrays, in function calls Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with arrays, in array literals Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with sparse arrays, in function calls Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with sparse arrays, in array literals ? Yes ? ? ? ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with strings, in function calls ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with strings, in array literals ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with astral plane strings, in function calls ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with astral plane strings, in array literals ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generator instances, in calls ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generator instances, in arrays ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generic iterables, in calls Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generic iterables, in arrays Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with instances of iterables, in calls Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with instances of iterables, in arrays Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§spreading non-iterables is a runtime error Yes Yes ? ? Yes[10] ? ? ? ? ? ? ? ? ? No[12] No[12] No[12] No[12] No[12] No[12] No[12] No[12] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§object literal extensions MDN (Mozilla Development Network) logo  6/6 6/6 6/6 6/6 6/6 5/6 5/6 5/6 5/6 5/6 5/6 5/6 5/6 5/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 2/6 0/6 5/6 6/6 5/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 4/6 4/6 4/6 4/6 0/6 6/6 6/6 6/6 6/6 6/6 0/6 2/6 2/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6
§computed properties Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§shorthand properties Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§shorthand methods Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] Yes[13] No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§string-keyed shorthand methods Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§computed shorthand methods Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§computed accessors Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§for..of loops MDN (Mozilla Development Network) logo  4/9 9/9 9/9 9/9 9/9 6/9 6/9 6/9 6/9 6/9 6/9 6/9 6/9 2/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 5/9 0/9 7/9 9/9 8/9 0/9 7/9 7/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 0/9 4/9 4/9 9/9 9/9 9/9 0/9 4/9 4/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 0/9 0/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9 9/9
§with arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with sparse arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with strings ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with astral plane strings ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generator instances ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generic iterables Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with instances of generic iterables Yes[11] Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§iterator closing, break ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§iterator closing, throw ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§octal and binary literals 2/4 2/4 4/4 4/4 4/4 2/4 2/4 2/4 2/4 2/4 2/4 2/4 2/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 2/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 2/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 0/4 4/4 4/4 4/4 4/4 0/4 0/4 0/4 4/4 4/4 4/4 0/4 2/4 2/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 0/4 0/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4 4/4
§octal literals Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[14] Flag[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§binary literals Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Flag[14] Flag[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§octal supported by Number() ? ? Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Flag[14] Flag[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§binary supported by Number() ? ? Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] Yes ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes ? Flag Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? Yes Yes Yes Yes ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Flag[14] Flag[14] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§template literals MDN (Mozilla Development Network) logo  5/7 6/7 6/7 6/7 6/7 5/7 5/7 5/7 2/7 5/7 5/7 5/7 5/7 6/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 5/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 6/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 6/7 7/7 7/7 0/7 0/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 0/7 7/7 7/7 7/7 0/7 5/7 5/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 5/7 0/7 0/7 7/7 7/7 7/7 6/7 6/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7 7/7
§basic functionality Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§toString conversion ? ? ? ? ? No No No No No No No No ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§tagged template literals Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§passed array is frozen Yes Yes Yes Yes Yes No No No No No No No No Yes ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§line break normalisation ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§TemplateStrings call site caching Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§TemplateStrings permanent caching Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes No[16] No[16] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§RegExp "y" and "u" flags MDN (Mozilla Development Network) logo  0/6 4/6 4/6 4/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 2/6 2/6 2/6 2/6 2/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 2/6 2/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 4/6 6/6 6/6 0/6 0/6 0/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 5/6 5/6 5/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6 6/6
§"y" flag ? ? No No Yes[10] ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"y" flag, lastIndex ? ? No No Yes[10] ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] Yes[15] Yes[15] Yes[15] Yes[15] Yes[15] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"u" flag ? Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"u" flag, non-BMP Unicode characters ? Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"u" flag, Unicode code point escapes ? Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No No Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§"u" flag, case folding ? Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ?[6] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No No Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§destructuring, declarations MDN (Mozilla Development Network) logo  14/22 20/22 21/22 21/22 21/22 20/22 20/22 20/22 20/22 20/22 20/22 20/22 20/22 12/22 21/22 21/22 21/22 21/22 21/22 21/22 21/22 21/22 0/22 0/22 0/22 0/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 0/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 11/22 0/22 12/22 21/22 19/22 0/22 0/22 0/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 0/22 22/22 22/22 22/22 0/22 0/22 0/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 21/22 0/22 0/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22 22/22
§with arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with sparse arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with strings Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with astral plane strings ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generator instances ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with generic iterables ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with instances of generic iterables ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§iterator closing ? Yes Yes[10] Yes[10] Yes[10] ? ? ? ? ? ? ? ? ? Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§trailing commas in iterable patterns Yes ? Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with objects Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§object destructuring with primitives Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§trailing commas in object patterns Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§throws on null and undefined Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§computed properties Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§multiples in a single var statement Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§nested Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§in for-in loop heads ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? ? ? ? ? ? ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§in for-of loop heads Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§in catch heads ? Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] Yes[9] ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? ? ? ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes No[17] ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§rest Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§defaults Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§defaults, let temporal dead zone ? ? Flag[18] Flag[18] Flag[18] Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No ? ? Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§destructuring, assignment MDN (Mozilla Development Network) logo  17/24 23/24 24/24 24/24 24/24 22/24 22/24 22/24 22/24 22/24 22/24 22/24 22/24 11/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 7/24 0/24 14/24 24/24 21/24 0/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 0/24 24/24 24/24 24/24 0/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 0/24 0/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24 24/24
§with arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? ? No No No No ? No No Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes Yes ? ? Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes
§with sparse arrays Yes Yes Yes[10] Yes[10] Yes[10] Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? ? ? No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes ? Yes Yes Yes ? ? ? Yes Yes Yes Yes Yes Yes Yes