Webpack external library access with Vue web components - vue.js

Question

I create a web component with vue-cli.3 in order to use it in other projects with the following command:
vue-cli-service build --target lib --name helloworld ./src/components/HelloWorld.vue
The component has a dependency on lodash. I don't want to bundle lodash with the component because lodash is going to be provided by the host application, so I configure webpack in vue.config.js like below:
module.exports = {
configureWebpack: {
externals: {
lodash: 'lodash',
root: '_'
}
}
}
So this way, I successfully compile the component without lodash.
In the host application (the one that will use the component), I add the source path of the newly created and compiled component into index.html:
<script src="http://localhost:8080/helloworld.umd.js"></script>
Register the component in App.vue:
<template>
<div id="app">
<demo msg="hello from my component"></demo>
</div>
</template>
<script>
export default {
name: "app",
components: {
demo: helloworld
}
};
</script>
The helloworld component renders without problems. Every feature of the component works without problems but as soon as I call a method of lodash, I get;
Uncaught TypeError: Cannot read property 'camelCase' of undefined
which means the component cannot access the lodash library that the host application uses.
I need to find a way to use the already bundled libraries in the host application from the components.
Is there a way?

Answer 1

The Vue config you used should work (see GitHub demo), so maybe there's something missing in your setup. I've listed the pertinent steps to arrive at the demo:
In public/index.html of a VueCLI-generated project, import Lodash from CDN with:
<script src="https://cdn.jsdelivr.net/npm/lodash#4.17.11/lodash.min.js"></script>
In the library component (src/components/HelloWorld.vue), the _ global can be used without importing lodash. For example, display a computed property that formats the msg prop with _.camelCase.
To avoid lint errors, specify _ as an ESLint global (/* global _ */).
In vue.config.js, configure Webpack to externalize lodash:
module.exports = {
configureWebpack: {
externals: {
lodash: {
commonjs: 'lodash',
amd: 'lodash',
root: '_' // indicates global variable
}
}
}
}
In package.json, edit the build script to be:
"build": "vue-cli-service build --target lib --name helloworld ./src/components/HelloWorld.vue",
Run npm run build, and then edit dist/demo.html to also include the <script> tag above.
Start an HTTP server in dist (e.g., python -m SimpleHTTPServer), and open dist/demo.html. Observe the effect of _.camelCase (from step 2) without console errors.
GitHub demo