Webpack: How can I combine two completely separate bundles using dynamic bundling

Question

I have spent a lot of time looking into this, but to no avail. I am aware of how code splitting and dynamic bundling works in Webpack using the import promise API.

Howevr, my use case is that I have two completely separate bundles, generated separately using different webpack builds. To give you perspective, I am building React components and there is a requirement to dynamically load a react component into the page that has been compiled in a different process. Is this possible in react? I do have control over both webpack builds, so I can exclude dependencies, etc.

Update: I just looked at Vue.js, and how it allows developers to register Vue.js components and then reference them later in the code. I could potentially load my Vue.js component scripts before my page script. I'm trying to see if I can do something similar in React.

Answer 1

Did I understand you correctly: you have essentially got

1. a library of custom React components (built by Webpack build #1)
2. a React app that needs to use some (all) of these components (built by Webpack build #2, totally separate from #1)

?

If yes, then read on.

The "Is this possible in react?" question should instead be "Is this possible in Webpack?", and the answer is "Yes". The following is tested with Webpack 2, but should also work with v.1.

Let's call your projects Lib (your React component library) and App (the library consumer).

In the Lib project:

1. Create an entry point file, say index.js, that exports all the custom React components like this:

   import {Button} from './button';
   import {DatePicker} from './DatePicker';
   import {TextBox} from './textBox';
   
   export const MyComponentLib = {
       Button,
       DatePicker,
       TextBox
   };
   

2. Update webpack.config.js to make the project's bundle a UMD library (could also be 'var'), and set the entry point to the above index.js file. Doing so will make your library available via a global variable named MyComponentLib (the name comes from the export above) in the consuming app later on:

    ...
    output: {
        path: './dist',
        filename: 'mylib.bundle.js',
        libraryTarget: 'umd'
    },
    ...
    entry: './index.js',
    ...
   

On to the App project:

1. In the index.html file you will have two <script> tags: one for mylib.bundle.js (the output of the Lib project), and another for the bundle of the App project itself. You might have more bundles (app, vendor etc.), I'm just simplifying things here.

2. Update webpack.config.js to mark the component library as external dependency. Here, MyComponentLib is, again, the name of the global variable the library is available at, and myComponents is the name to use in import statements:

   ...
   externals: {
       myComponents: 'MyComponentLib'
   }, 
   ...
   

Now, in App you can import a component like this:

import {DatePicker} from 'myComponents';

This will dynamically load DatePicker from the component library at run time via the global variable.

Bonus: if you use eslint, you don't want it to complain about missing modules that you know are external; add this to your .eslintrc:

...
"settings": {
      "import/core-modules": ["myComponents"]
},
...