Getting started with VUE3 development: dynamic loading and registration using components

VUE3 is currently one of the most popular front-end frameworks. It has attracted more and more developers with its ease of use, flexibility, performance optimization and other advantages. In VUE3, using components is a very common operation, but because large projects may require dynamic loading and registration of components, in this article we will introduce how to use components to dynamically load and register.

First of all, we need to understand how components are registered in VUE3. In VUE3, components can be registered using object literals or using the Vue.createApp method. The following is a simple example of a custom component:

<template>
  <div>{{ message }}</div>
</template>

<script>
  export default {
    props: {
      message: {
        type: String,
        required: true
      }
    }
  }
</script>

This component receives a property named "message", which must be of string type, otherwise an error will be reported. Now let's take a look at how to dynamically load and register components.

Dynamic loading of components

Dynamic loading of components means that when we run the application, the component is dynamically loaded only when it is really needed. Doing so can improve your application's performance and responsiveness.

VUE3 provides the feature of asynchronous component. You can define the component as an asynchronous component and then load it when needed. The following is an example of an asynchronous component:

<template>
  <div>{{ message }}</div>
</template>

<script>
  export default {
    props: {
      message: {
        type: String,
        required: true
      }
    }
  }
</script>

When using an asynchronous component, we need to define the component as an asynchronous function. In this function, we can use import() to load the component asynchronously and return the component after the loading is complete.

The following is a more complete asynchronous component registration example:

<template>
  <div>
    <h1>Welcome to my app!</h1>
    <async-component :message="message" />
  </div>
</template>

<script>
  const AsyncComponent = () => ({
    // 加载异步组件
    component: import('./AsyncComponent.vue'),
    // 显示加载中
    loading: LoadingComponent,
    // 显示加载错误
    error: ErrorComponent,
    // 展示组件
    delay: 200,
    // 如果组件定义了名字，则可以直接使用这个字面量
    // name: 'my-component-name'
  })

  export default {
    components: {
      AsyncComponent
    },
    data() {
      return {
        message: 'Hello, world!'
      }
    }
  }
</script>

In this example, we use the dynamic loading method of Vue asynchronous components, first define an asynchronous component, and then use it way to render it in the template. Since AsyncComponent is just a function, we don't need to load the component when the component is initialized, it will be loaded automatically when needed.

When defining AsyncComponent, we can specify a function with a return value of promise as the component attribute of the component for asynchronous loading of components. If your component requires some preloaded components, you can specify the names of these components using the loading and error options. After the component loads successfully, we can use the delay option to specify a delay before the actual component is rendered.

Component registration

In VUE3, we can register components using global registration or local registration. The difference between the two is whether the component is registered as global or limited to that component's parent.

Using global registration, components can be used throughout the entire application, while local registration can only be used between parent components and child components. The following are examples of globally registered components and locally registered components:

Global registration component

The way to globally register a component is to mount the component to the components option of the Vue object. The following is a global registration Example of a component:

<template>
  <div>
    <my-component :message="message" />
  </div>
</template>

<script>
  import MyComponent from './MyComponent.vue'

  export default {
    components: {
      MyComponent
    },
    data() {
      return {
        message: 'Hello, world!'
      }
    }
  }
</script>

In this example, we import the MyComponent component and place it in the components option of the Vue instance, and then use my-component in the template to display it.

Local registration components

Local registration components can only be used in the current component and its subcomponents. The following is an example of a local component registration:

<template>
  <div>
    <my-component :message="message" />
  </div>
</template>

<script>
  import MyComponent from './MyComponent.vue'

  export default {
    components: {
      'my-component': MyComponent
    },
    data() {
      return {
        message: 'Hello, world!'
      }
    }
  }
</script>

In this example, we register MyComponent as a local component of the current component. We set the component name to "my-component" in the components property and then pass the component instance as the value.

Summary

In this article, we learned how to use components in VUE3 to dynamically load and register components. We achieve this by using asynchronous components and registration of global and local components. Through these technologies, we can achieve better performance and flexibility in VUE3.

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