js 类成员用箭头函数赋值编译出错

js中类成员可以用什么样的方式定义,好多地方都没有说明,今天调试一段代码正好又遇到了这个问题,代码如下:

import React from 'react'
import ReactDOM from 'react-dom'
import iScroll from 'iscroll'

import './example.css'
import ReactIScroll from 'react-iscroll'

const iScrollOptions = {
    mouseWheel: true,
    scrollbars: true,
    scrollX: true
};

class JsPage extends React.Component {

    constructor(props) {
        super(props)

        const list = [];
        const len = 30;

        for(let i = 0; i < len; i++) {
            list.push(i+1)
        }

        this.state = {
            y: 0,
            isScrolling: false,
            list: list,
            lastId: len
        }
    }

    onScrollStart = () => {
        this.setState({isScrolling: true})
    }; 

    onScrollEnd = (iScrollInstance) => {
        this.setState({isScrolling: false, y: iScrollInstance.y})
    };

    addRow = (ev) => {
        ev.preventDefault()

        const list  = this.state.list,
              newId = this.state.lastId + 1;

        list.push(newId)

        this.setState({list: list, lastId: newId})
    };

    removeRow = (ev) => {
        ev.preventDefault()

        const list = this.state.list;

        list.shift()

        this.setState({list: list})
    };

    onScrollRefresh = (iScrollInstance) => {
        const hasVerticalScroll = iScrollInstance.hasVerticalScroll

        if(this.state.canVerticallyScroll !== hasVerticalScroll) {
            this.setState({canVerticallyScroll: hasVerticalScroll})
        }
    };

    render() {
        const listOfLi = [],
              len = this.state.list.length;
        let i = 0;

        for(i; i < len; i++) {
            listOfLi.push(<li key={i}>Pretty row {this.state.list[i]}<span className="beyond">I'm beyond</span></li>)
        }
        return (
            <div>
                <div id="header">
                    <button onClick={this.removeRow} className="button">Remove first row</button>
                    React iScroll component example
                </div>
                <div id="wrapper">
                    <ReactIScroll iScroll={iScroll}
                                  options={iScrollOptions}
                                  onRefresh={this.onScrollRefresh}
                                  onScrollStart={this.onScrollStart}
                                  onScrollEnd={this.onScrollEnd}>
                        <div style={{width: "110%"}}>
                            <ul>
                                {listOfLi}
                            </ul>
                        </div>
                    </ReactIScroll>
                </div>
                <div id="footer">
                    <button onClick={this.addRow} className="button">Add one row</button>
                    status: {this.state.isScrolling ? 'Scrolling' : 'Standby' } |
                    can vertically scroll: {this.state.canVerticallyScroll ? 'Yes' : 'No'}
                </div>
            </div>
        )
    }
}

export default JsPage;

报错信息如下:

ERROR in ./master/jsx/components/jspage.jsx
Module build failed: SyntaxError: C:/codes/ihotel/src/jspage.jsx: Unexpected token (34:18)
  32 |     }
  33 |
> 34 |     onScrollStart = () => {
     |                   ^
  35 |         this.setState({isScrolling: true})
  36 |     };
  37 |

类成员不能用箭头函数赋值吗?

---

成员函数这样声明就好了：

onScrollStart(){
    this.setState({isScrolling: true});
}

注意，结尾也没有分号哦

确实不能用箭头函数，因为Arrow functions are always anonymous

---

像 render 那样写成成员函数不好吗？

或者:

name: ()=>{}

---

用到了ES类属性赋值的特性，需要安装相应的babel

npm install babel-preset-stage-0

ｗebpack 配置

module: {
    loaders: [
        {
            test: /\.(jsx|js)$/,
            loader: 'babel-loader',
            exclude: /node_modules/,
            query: {
                presets: ['react', 'es2015', 'stage-0']
            }
        }
    ]
}