解析错误handleDismissClick = e =>

Question

SyntaxError: /Users/mumuhou/github/web/react/examples/basic-commonjs/index.js: Unexpected token (7:21) while parsing file: /Users/mumuhou/github/web/react/examples/ basic-commonjs/index.js

我的代码：

'use strict';

import React, { Component, PropTypes } from 'react'
import ReactDOM from 'react-dom'

class App extends Component {
  handleDismissClick = e => {
    e.preventDefault()
  }

  render() {
    var elapsed = Math.round(this.props.elapsed  / 100);
    var seconds = elapsed / 10 + (elapsed % 10 ? '' : '.0' );
    var message =
      'React has been successfully running for ' + seconds + ' seconds.';

    return <p>{message}</p>;
  }
}

var start = new Date().getTime();

setInterval(function() {
  ReactDOM.render(
    <App elapsed={new Date().getTime() - start} />,
    document.getElementById('container')
  );
}, 200);

我有配置 es2015

Answer 1

class App extends Component {
  handleDismissClick = e => {
    e.preventDefault()
  }
}

是public class fields 提案。为了让 Babel 理解并转换它，你必须加载 corresponding plugin，或者直接使用 stage-2 preset。