CODEWITHSUNDEEP
javascriptecmascript-6babeljs
Estus Flask
Estus Flask

Reputation: 222513

Babel 'protoToAssign' transformer and ES6 class inheritance

Here is simple plunker example involving class inheritance, with shims and Babel options being set to stage: 0, loose: 'all':

class Hello {
  static address = ', world!';
  greeting = 'Hello';

  constructor() {
    this.greet();
  }

  greet() {
    document.write(this.greeting + Hello.address);
  }
}

class Hi extends Hello {
  greeting = 'Hi';

  constructor() {
    super();
  }
}

new Hi().greet();

Apparently, it works as it should in IE5.5+.

What are the circumstances where Babel spec.protoToAssign transformer can be beneficial (or undesirable) for ES6/ES7 transpiled OOP code that is targeted to legacy browsers?

Upvotes: 2

Views: 782

Answers (1)

loganfsmyth
loganfsmyth

Reputation: 161467

ES6 class inheritance also means that

Hi.address

would work because Hi inherits from Hello. Without protoToAssign, this will not work in IE<=10.

The general case is exactly as described on that page however. IE<=10 does not support assignment of __proto__ so if you rely on behavior that relied on it, it will not work.

This is all covered in the caveats page for Babel.

Upvotes: 2

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