Support async/await

[gaearon]

Test plan:

importReact,{Component}from'react';importlogofrom'./logo.svg';import'./App.css';classAppextendsComponent{asynccomponentDidMount(){try{awaitfetch('http://google.com');}catch(lol){alert('oh noes')}}render(){return(<divclassName="App"><divclassName="App-header"><imgsrc={logo}className="App-logo"alt="logo"/><h2>Welcome to React</h2></div><pclassName="App-intro">
To get started, edit <code>src/App.js</code> and save to reload.
</p></div>);}}exportdefaultApp;

It worked.

[fson]

Out of curiosity, is there a reason we use transform-async-to-generator to first transform async functions to generators and then regenerator to transform them to ES5? (Regenerator can also transform async functions directly, in which case the async-to-generator won't be needed.)

I've tested the Regenerator-only solution with following config:

require.resolve('babel-plugin-syntax-async-functions'),[require.resolve('babel-plugin-transform-regenerator'),{asyncGenerators: false,generators: true,async: true}],

and it compiled to more or less the same code except it uses only the regenerator runtime and not the _asyncToGenerator helper from Babel. I don't know, if there are some minor differences in the runtime behaviour of these alternatives.

If you want to switch, I can send a pull request with this config I have.

P.S. It's very cool to have async/await supported by create-react-app! This was the reason I had to eject my config and I've been planning to make a PR to add them, but you beat me to it 😎

[gaearon]

Yeah, PR would be welcome. I had no idea what’s the right way to integrate this. 😄