Prevent specific .vue components from being bundled

Question

Problem: In my vue-cli 4 app, I'd like to have build: script, which generates production bundle, with specific .vue-components not being included in some cases. In other cases they should be included. Also, these components are stored in app itself - not in external library.

I've tried: to import .vue-components dynamically - let's say I have an array:

const customPreset = ['WidgetFirst', 'WidgetSecond', ...]

And empty object:

const widgets = {}

So I've tried to make something like this:

customPreset.forEach(v => { Object.assign(widgets, { [v]: () => import('./' + v + '.vue') }) })
export default widgets

Changing customPreset to some other array would allow to import another set of components...

But that doesn't work, because import() cannot operate with expressions.

So, what could be done to include various .vue-components into production bundle in various cases? Maybe it could be achieved through tweaking vue.config.js?

Answer 1

What you are looking for is lazy loaded components. In Vue they are available at multiple points.

1. In vue-router - you can import components per route, to load only when they are needed:

This is how to define an async component that will be automatically code-split by webpack:

const Foo = () => import('./Foo.vue')

You can also group components in the same chunk:

const Foo = () => import(/* webpackChunkName: "group-foo" */ './Foo.vue')
const Bar = () => import(/* webpackChunkName: "group-foo" */ './Bar.vue')
const Baz = () => import(/* webpackChunkName: "group-foo" */ './Baz.vue')

2. Second option is Dynamic/Async components, which can be used in .vue files like this:

Vue.component(
  'async-webpack-example',
  // The `import` function returns a Promise.
  () => import('./my-async-component')
)

It even support loading state, straight from the box:

const AsyncComponent = () => ({
  // The component to load (should be a Promise)
  component: import('./MyComponent.vue'),
  // A component to use while the async component is loading
  loading: LoadingComponent,
  // A component to use if the load fails
  error: ErrorComponent,
  // Delay before showing the loading component. Default: 200ms.
  delay: 200,
  // The error component will be displayed if a timeout is
  // provided and exceeded. Default: Infinity.
  timeout: 3000
})