The difference between Vue3 and Vue2: more powerful asynchronous component loading

The difference between Vue3 and Vue2: More powerful asynchronous component loading

Vue is a popular JavaScript framework that is widely used to develop web applications. Vue3 is the latest version of the Vue framework and has many exciting new features and improvements compared to Vue2. One of the major improvements is the enhancement of asynchronous component loading. In this article, we will focus on the improvements in asynchronous component loading of Vue3 compared to Vue2, and attach relevant code examples.

In Vue2, developers can implement asynchronous component loading by using factory functions or dynamic import syntax. However, these methods have some limitations in some cases. For example, the factory function needs to be defined before globally registering the component and cannot be imported directly using the ES module. The dynamic import syntax needs to be implemented with the help of packaging tools such as Webpack.

Vue3 makes asynchronous component loading more convenient and flexible by introducing the defineAsyncComponent function. defineAsyncComponentThe function accepts a parameter, which can be a Promise object that returns the component definition or a function that returns the component definition. Here is a simple example:

import { defineAsyncComponent } from 'vue';

const AsyncComponent = defineAsyncComponent(() => {
  return import('./AsyncComponent.vue');
});

In the above code, we define an asynchronous component AsyncComponent using the defineAsyncComponent function. The definition of the asynchronous component is achieved by dynamically importing the ./AsyncComponent.vue file.

In addition to simplifying the definition of asynchronous components, Vue3 also introduces a new built-in component Suspense to handle the loading process of asynchronous components gracefully. SuspenseThe component can wrap multiple asynchronous components and render a waiting prompt before these asynchronous components are loaded. Once all asynchronous components are loaded, the Suspense component will render them together. Here is an example:

<template>
  <Suspense>
    <template #default>
      <AsyncComponent1 />
      <AsyncComponent2 />
      <AsyncComponent3 />
    </template>
  
    <template #fallback>
      <div>Loading...</div>
    </template>
  </Suspense>
</template>

<script>
import { Suspense, defineAsyncComponent } from 'vue';

const AsyncComponent1 = defineAsyncComponent(() => {
  return import('./AsyncComponent1.vue');
});

const AsyncComponent2 = defineAsyncComponent(() => {
  return import('./AsyncComponent2.vue');
});

const AsyncComponent3 = defineAsyncComponent(() => {
  return import('./AsyncComponent3.vue');
});
</script>

In the above code, we use the Suspense component to wrap three asynchronous components AsyncComponent1, AsyncComponent2 and AsyncComponent3. Before these asynchronous components are loaded, the Suspense component will render a waiting prompt showing Loading.... Once all asynchronous components are loaded, they are rendered together.

It should be noted that Suspense components can only wrap asynchronous components and cannot be nested. However, more complex asynchronous component loading logic can be implemented by nesting multiple Suspense components.

To summarize, Vue3 makes the loading of asynchronous components more convenient and flexible by introducing the defineAsyncComponent function and the Suspense component. Developers can more easily define and manage asynchronous components without relying on complex factory functions or packaging tools.

The above is the improvement of Vue3 in asynchronous component loading compared to Vue2. I hope this article will help you understand the new features of Vue3. If you are interested in Vue3, you might as well try using it to develop your next web application!

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