javascript - How can I alert supported EcmaScript version of the browser? -

javascript - How can I alert supported EcmaScript version of the browser? -

is there way alert supported ecmascript version of current environment run javascript?

short answer: no.

long answer: first of all, browsers doesn't implement ecmascript language based on specification (e.g. javascript firefox, jscript microsoft). often, can implement part of standard, , finish standard in next version of language (it happened in javascript 1.8 / 1.8.1 / 1.8.5 es5 example, see new in javascript).

plus, anticipate standard: see for...of or let, mozilla has since years, part of es6.

so, can't es version supported environment; can testing functionality interested in, , utilize them. in of case, apply shim, possible, emulate functionality, es5.

javascript ecmascript-5