> How do you define just fine? It's taken us many years to migrate EMCA versions only to have multiple incompatible runtimes.
ECMAScript versions are forward-compatible. Any valid ECMAScript 3 code is also valid 5.1, 2015, 2016, etc.
I'm not sure what migration you're talking about. If you mean using new language features before your runtime targets support them, that's kinda on you. Even so, the ecosystem has tons of robust solutions for supporting legacy interpreters. Most notably, Babel does a wonderful job of transpiling to lower language-version targets.
ECMAScript versions are forward-compatible. Any valid ECMAScript 3 code is also valid 5.1, 2015, 2016, etc.
I'm not sure what migration you're talking about. If you mean using new language features before your runtime targets support them, that's kinda on you. Even so, the ecosystem has tons of robust solutions for supporting legacy interpreters. Most notably, Babel does a wonderful job of transpiling to lower language-version targets.