'use strict'
const path = require('path')
const utils = require('./utils')
const config = require('../config')
const vueLoaderConfig = require('./vue-loader.conf')
const webpack = require('webpack')  //这里引入webpack

function resolve (dir) {
  return path.join(__dirname, '..', dir)
}



module.exports = {
  context: path.resolve(__dirname, '../'),
  entry: {
    app: './src/main.js'
  },
  output: {
    path: config.build.assetsRoot,
    filename: '[name].js',
    publicPath: process.env.NODE_ENV === 'production'
      ? config.build.assetsPublicPath
      : config.dev.assetsPublicPath
  },
  resolve: {
    extensions: ['.js', '.vue', '.json'],
    alias: {
      'vue$': 'vue/dist/vue.esm.js',
      '@': resolve('src'),

           // 如果是自己下载的jq文件，则用下面方式修改为存放目录
          // 'jquery': path.resolve(__dirname, '../src/assets/libs/jquery/jquery.min'),
          // 如果使用NPM安装的jQuery，则直接引入即可
      'jquery': 'jquery' 
    }
  },
  module: {
    rules: [
      {
        test: /.vue$/,
        loader: 'vue-loader',
        options: vueLoaderConfig
      },
      {
        test: /.js$/,
        loader: 'babel-loader',
        include: [resolve('src'), resolve('test'), resolve('node_modules/webpack-dev-server/client')]
      },
      {
        test: /.(png|jpe?g|gif|svg)(?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('img/[name].[hash:7].[ext]')
        }
      },
      {
        test: /.(mp4|webm|ogg|mp3|wav|flac|aac)(?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('media/[name].[hash:7].[ext]')
        }
      },
      {
        test: /.(woff2?|eot|ttf|otf)(?.*)?$/,
        loader: 'url-loader',
        options: {
          limit: 10000,
          name: utils.assetsPath('fonts/[name].[hash:7].[ext]')
        }
      }
    ]
  },
  node: {
    // prevent webpack from injecting useless setImmediate polyfill because Vue
    // source contains it (although only uses it if it's native).
    setImmediate: false,
    // prevent webpack from injecting mocks to Node native modules
    // that does not make sense for the client
    dgram: 'empty',
    fs: 'empty',
    net: 'empty',
    tls: 'empty',
    child_process: 'empty'
  },
//在最后添加一个plugins配置
  plugins: [
    new webpack.ProvidePlugin({
        $: "jquery",
        jQuery: "jquery"
    })
 ],
}

<script>
//引入jquery就可以使用了
import $ from 'jquery'
export default {
  name: 'HelloWorld',
  data () {
    return {
      msg: 'Welcome to Your Vue.js App'
    }
  },
  created(){
     //已经能打印出来了
    console.log($)
  }
}
</script>

const webpack = require('webpack')
 
module.exports = {
  chainWebpack: config => {
    config.plugin('provide').use(webpack.ProvidePlugin, [{
      $: 'jquery',
      jquery: 'jquery',
      jQuery: 'jquery',
      'window.jQuery': 'jquery'
    }])
  }

import $ from 'jquery'