webpack配置es6为什么报错

Question

只装了babel-core,babel-loader,
然后提示improt这个语法错误

module.exports={
    entry:[
        './index.js',
    ],
    output:{
        filename:'build.js',
    },
    module: {
      loaders: [
        { test: /\.js$/, exclude: /node_modules/, loader: "babel-loader" }
      ]
    }
}

//index.js
import {sum, pi} from "./b.js";
console.log("2π = " + sum(pi, pi));

//b.js
export function sum(x, y) {
  return x + y;
}
export var pi = 3.141593;

build.js:54 Uncaught SyntaxError: Unexpected token import

Answer 1

你没有配置关于es语法的东西，当然会报错啊
你这样配置一下

并且需要安装es6语法包

Answer 2

加上.babelrc文件

声明

{
  "presets": ["es2015"]
}

Answer 3

安装

    "babel-core",
    "babel-loader",
    "babel-preset-es2015",

然后

loaders: [
            { test: /\.js$/, loader: 'babel?presets=es2015' },
         ]