如何在WebPack/Babel构建中使用CustomElement v1 polyfill？

Question

我遇到了一些麻烦，让这个WebComponents polyfill+native-shim在所有设备上都能正常工作，尽管WebPack。

关于我的设置的一些背景：*Webpack2+babel-6*应用程序是用ES6编写的，转换到ES5*导入一个用ES6编写的node_module包，它定义/注册应用程序中使用的customElement

因此相关的webpack开发人员配置如下所示：

const config = webpackMerge(baseConfig, {
  entry: [
    'webpack/hot/only-dev-server',
    '@webcomponents/custom-elements/src/native-shim',
    '@webcomponents/custom-elements',
    '<module that uses CustomElements>/dist/src/main',
    './src/client',
  ],
  output: {
    path: path.resolve(__dirname, './../dist/assets/'),
    filename: 'app.js',
  },
  module: {
    rules: [
      {
        test: /\.js$/,
        loader: 'babel-loader',
        options: {
          cacheDirectory: true,
        },
        include: [
          path.join(NODE_MODULES_DIR, '<module that uses CustomElements>'),
          path.join(__dirname, '../src'),
        ],
      },
    ],
  },
...

键取方式:*我需要在<使用CustomElements>的模块>之前加载CustomElements>*我需要在我的应用程序源之前加载<使用CustomElements>的模块，所以我们要转换它（因此包含在Babel-Loader中）。

然而，在现代ES6浏览器（即桌面Chrome浏览器）中，上述功能与预期的一样有效

它在较旧的浏览器中不起作用。我在较旧的浏览器（例如iOS 8）中遇到以下错误：

SyntaxError: Unexpected token ')'

指向native-shim PollyFill中的打开匿名函数：

(() => {
  'use strict';

  // Do nothing if `customElements` does not exist.
  if (!window.customElements) return;

  const NativeHTMLElement = window.HTMLElement;
  const nativeDefine = window.customElements.define;
  const nativeGet = window.customElements.get;

因此在我看来,native-shim需要传输到ES5:

        include: [
+         path.join(NODE_MODULES_DIR, '@webcomponents/custom-elements/src/native-shim'),
          path.join(NODE_MODULES_DIR, '<module that uses CustomElements>'),
          path.join(__dirname, '../src'),
        ],

app.js:1 Uncaught TypeError: Failed to construct 'HTMLElement': Please use the 'new' operator, this DOM object constructor cannot be called as a function.
    at new StandInElement (native-shim.js:122)
    at HTMLDocument.createElement (<anonymous>:1:1545)
    at ReactDOMComponent.mountComponent (ReactDOMComponent.js:504)
    at Object.mountComponent (ReactReconciler.js:46)
    at ReactCompositeComponentWrapper.performInitialMount (ReactCompositeComponent.js:371)
    at ReactCompositeComponentWrapper.mountComponent (ReactCompositeComponent.js:258)
    at Object.mountComponent (ReactReconciler.js:46)
    at Object.updateChildren (ReactChildReconciler.js:121)
    at ReactDOMComponent._reconcilerUpdateChildren (ReactMultiChild.js:208)
    at ReactDOMComponent._updateChildren (ReactMultiChild.js:312)

..它将我带到native-shim中的constructor()行：

  window.customElements.define = (tagname, elementClass) => {
    const elementProto = elementClass.prototype;
    const StandInElement = class extends NativeHTMLElement {
      constructor() {

呵。所以我很不清楚我们是如何在基于webpack的构建中包含这一点的，其中使用CustomElements的依赖关系是ES6（并且需要Transspilling）。

• 将本机填充转换到es5不起作用
• 在包入口点顶部使用原生shim（原样）对iOS 8无效，但对Chrome有效
• 不包括Chrome和iOS的native-shim中断

{
  "presets": [
    ["es2015", { "modules": false }],
    "react"
  ],
  "plugins": [
    "transform-custom-element-classes",
    "transform-object-rest-spread",
    "transform-object-assign",
    "transform-exponentiation-operator"
  ],
  "env": {
    "test": {
      "plugins": [
        [ "babel-plugin-webpack-alias", { "config": "./cfg/test.js" } ]
      ]
    },
    "dev": {
      "plugins": [
        "react-hot-loader/babel",
        [ "babel-plugin-webpack-alias", { "config": "./cfg/dev.js" } ]
      ]
    },
    "dist": {
      "plugins": [
        [ "babel-plugin-webpack-alias", { "config": "./cfg/dist.js" } ],
        "transform-react-constant-elements",
        "transform-react-remove-prop-types",
        "minify-dead-code-elimination",
        "minify-constant-folding"
      ]
    },
    "production": {
      "plugins": [
        [ "babel-plugin-webpack-alias", { "config": "./cfg/server.js" } ],
        "transform-react-constant-elements",
        "transform-react-remove-prop-types",
        "minify-dead-code-elimination",
        "minify-constant-folding"
      ]
    }
  }
}

Answer 1

我能够通过下面的.babelrc插件管道实现类似的功能。看起来只有https://babeljs.io/docs/plugins/transform-es2015-classs/和https://babeljs.io/docs/plugins/transform-es2015-classs/，但我真的不记得它们具体解决了什么问题：

{
  "plugins": [
    "transform-runtime",
    ["babel-plugin-transform-builtin-extend", {
      "globals": ["Error", "Array"]
    }],
    "syntax-async-functions",
    "transform-async-to-generator",
    "transform-custom-element-classes",
    "transform-es2015-classes"
  ]
}