引导程序的 Webpack 构建错误

Question

当我开始构建时，会出现以下“警告”。 我该如何解决这个问题？

除了“$ npm run build”之外，还有没有实时构建的命令？ 例如）$ sass --watch

或实时预览

  $ npm run build

    > bootstrap-webpack@1.0.0 build /Users/suk/myweb
    > webpack

    Hash: 62314a5e1bd8f234994f
    Version: webpack 4.16.1
    Time: 7100ms
    Built at: 2018-07-18 19:27:20
        Asset     Size  Chunks                    Chunk Names
    bundle.js  328 KiB       0  [emitted]  [big]  main
    [0] ./src/app.js 45 bytes {0} [built]
    [4] (webpack)/buildin/global.js 489 bytes {0} [built]
    [5] ./src/scss/app.scss 1.35 KiB {0} [built]
    [6] ./node_modules/css-loader!./node_modules/postcss-loader/lib??ref--4-2!./node_modules/sass-loader/lib/loader.js!./src/scss/app.scss 165 KiB {0} [built]
        + 6 hidden modules

    WARNING in configuration
    The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
    You can also set it to 'none' to disable any default behavior. Learn more: https://webpack.js.org/concepts/mode/

    WARNING in asset size limit: The following asset(s) exceed the recommended size limit (244 KiB).
    This can impact web performance.
    Assets: 
      bundle.js (328 KiB)

    WARNING in entrypoint size limit: The following entrypoint(s) combined asset size exceeds the recommended limit (244 KiB). This can impact web performance.
    Entrypoints:
      main (328 KiB)
          bundle.js


    WARNING in webpack performance recommendations: 
    You can limit the size of your bundles by using import() or require.ensure to lazy load some parts of your application.
    For more info visit https://webpack.js.org/guides/code-splitting/

Answer 1

WARNING in configuration
    The 'mode' option has not been set, webpack will fallback to 'production' for this value. Set 'mode' option to 'development' or 'production' to enable defaults for each environment.
    You can also set it to 'none' to disable any default behavior. Learn more: https://webpack.js.org/concepts/mode/

可以通过添加 --mode 生产（或开发）来修复此错误，具体取决于您所针对的环境。或者，你也可以添加你的 webpack 配置：

{
  mode: "development"
  ...
}

其他的只是提示，为了让你的应用程序更好，你可以忽略它们，或者你可以通过将它添加到你的 webpack 配置来禁用它：

performance: {hints: false}

要将其添加到命令行，请编辑您的 package.json 并使用 webpack 添加此 alogside：

webpack --mode development.

让 webpack 监视变化：

webpack --mode development --watch