Webpack4+MobX State Tree+Babel环境下IE11报Object.assign错误，选哪个Babel插件？

Hey there! Let's work through this IE11 error together. First, the root cause is clear: IE11 doesn't natively support Object.assign, and the error is popping up in mobx-state-tree's library code (not your own source files)—that's a critical detail here.

两者的核心区别 #

• babel-plugin-transform-object-assign
  This plugin only transforms Object.assign calls in your own project code, converting them into compatibility-friendly equivalent logic. However, it won't touch code inside node_modules (like mobx-state-tree's files). Since your error comes from a third-party library, this plugin can't fix the problem for you.

• babel-polyfill
  It works by adding missing JavaScript APIs to the global environment, including Object.assign. Once you include it, every piece of code—whether yours or a third-party library's—will use this polyfilled implementation when calling Object.assign. This is exactly what you need here, because the error originates from mobx-state-tree's code.

推荐解决方案 #

Go with babel-polyfill (or the more modern core-js, which is the recommended approach for Babel 7+):

1. Install the dependency:

   npm install --save babel-polyfill
   

2. Import it at the very top of your project's entry file (like index.js):

   import 'babel-polyfill';
   

For Babel 7+ users, a better practice is to use core-js with @babel/preset-env to auto-include only the polyfills IE11 needs:

• Install core-js:

  npm install --save core-js@3
  

• Update your Babel config:

  {
    "presets": [
      [
        "@babel/preset-env",
        {
          "targets": {
            "ie": "11"
          },
          "useBuiltIns": "usage",
          "corejs": 3
        }
      ]
    ]
  }
  

  This setup will automatically inject required polyfills (including Object.assign) based on your target browser, no manual import needed.

总结 #

Since your error comes from a third-party library, babel-plugin-transform-object-assign can't help—it only processes your own code. You need babel-polyfill (or core-js) to globally patch the missing Object.assign API, so IE11 can run mobx-state-tree correctly.

内容的提问来源于stack exchange，提问作者chobo2