resolve: {
  extensions: ['', '.js', '.vue'],
  fallback: [path.join(__dirname, '../node_modules')],
  alias: {
    'vue$': 'vue/dist/vue.common.js',
    'src': path.resolve(__dirname, '../src'),
    'assets': path.resolve(__dirname, '../src/assets'),
    'components': path.resolve(__dirname, '../src/components')
  }
},

'components': path.resolve(__dirname, '../src/components')为例：
路径可以直接写'components/.......'
不用再'./components/...'这样一级一级目录去找了