4 ms·

> Can someone explain the reasoning behind having any kind of backwards compatibility? Not breaking millions of websites.

• pluma 11y ago
  *billions. Maybe even orders of magnitude more than that.
• alkonaut 11y ago
  In what way would a cleaner ES6 break websites? Browsers aren't going to stop supporting ES5.
  • bzbarsky 11y ago
    Browsers aren't likely to implement two separate languages either. Furthermore, forcing people to pick between "ES5" and "ES6" if they just want to use a single ES6 feature is pretty bad. So your fundamental choices are really an ES6 that is backwards-compatible or an ES6 that is not used.
    • alkonaut 11y ago
      On the other hand forcing newcomers to learn the warts of ES5 when they could learn what is becoming a reasonably elegant language isn't ideal either. Two scoping rules, for example. An ES-latest runtime + transpilers would be all that browsers needed.
      • bzbarsky 11y ago
        This has in fact been debated back and forth on the es-discuss mailing list and in TC39, especially given experiences with strict mode. The decision was generally made to not have more modes and to just have a single JS language. You don't have to agree with that decision obviously, but this isn't something that happened willy-nilly.