Lexical binding in class.

[hemanth]

Was trying the beta version and noticed:

class Counter extends React.Component {
  static propTypes = { initialCount: React.PropTypes.number };
  static defaultProps = { initialCount: 0 };
  state = { count: this.props.initialCount };
  tick = () =>  this.setState({ count: this.state.count + 1 });
  render = () => {
    return (
      <div onClick={this.tick()}>
        Clicks: {this.state.count}
      </div>
    );
  }
}

Would bomb on jsx --harmony with Parse Error: Unexpected token =

AFAIK, new on a arrow function definitions will throw an error is not a constructor and it doesn't have a prototype as well, so I guess it can't be used with class...

//cc @sebmarkbage

[gaearon]

I don't think it's a supported syntax (yet).

See here:

Wait, assigning to properties seems like a very imperative way of defining classes! You're right, however, we designed it this way because it's idiomatic. We fully expect a more declarative syntax for property initialization to arrive in future version of JavaScript. It might look something like this

Nevertheless I would be thrilled if this was supported in transpilers liberal to experiments such as 6to5. @sebmarkbage Is there any kind of spec for this? I talked to @sebmck and he doesn't mind getting this into 6to5.

[sebmarkbage]

There is no official proposal yet, no. I assume it will look something like TypeScript, but the reflective aspects and scoping rules will probably differ a bit.

[dashed]

@sebmarkbage Are you currently in the midst of writing a spec for this?

[sophiebits]

Not really a React issue, so I'm going to close this out. Lots of discussion on the babel issue:

babel/babel#619

[hemanth]

👍

[peter-mouland]

could someone update the babel issue link?
They have moved to phabricator!!
https://phabricator.babeljs.io/

[hawkrives]

I'm reasonably sure it's https://phabricator.babeljs.io/T619