What does export default mean in Vue

export default is not only used to export Vue components, it also allows: exporting a single default value for a module. When exporting components, you allow custom names to be used when importing. Package and export component dependencies for easy import and use.

export default in Vue: not just export

You may have seen export default countless times and think it is a way to export Vue components, right? In fact, this is just the tip of the iceberg. Understanding the essence of export default can allow you to write more elegant and easier to maintain Vue code, and can even help you avoid some common pitfalls.

This article will take you into the export default mechanism, telling you what it is, why it is easy to use, and how to use it better. After reading, you will have a deeper understanding of how Vue components are exported and be able to write more efficient code.

Let’s start with the basics. export default is a syntactic sugar in the ES6 module system. It allows you to export a single default value from a module. In Vue, it is usually used to export Vue components. This is different from the export keyword. export can export multiple named items, while export default can only export one.

Let's take a look at a simple example:

 <code class="javascript">// MyComponent.vue export default { name: 'MyComponent', data() { return { message: 'Hello, world!' } }, template: `<div>{{ message }}</div>` }</code>

This code defines a Vue component named MyComponent and exports it using export default . This allows you to import and use this component directly in other modules:

 <code class="javascript">// App.vue import MyComponent from './MyComponent.vue' export default { components: { MyComponent }, template: `<div><mycomponent></mycomponent></div>` }</code>

Simple and clear, right? But here is a detail that you may have overlooked: export default components exported, you can name them as you like when importing. You can write this way:

 <code class="javascript">import MyCustomName from './MyComponent.vue'</code>

MyCustomName now points to the components exported by MyComponent.vue . This is very convenient in refactoring or large projects, avoiding naming conflicts. However, this also brings a small risk: if your team members are named at will, the readability and maintenance of the code will be reduced. Therefore, it is best to establish a naming specification within the team.

Next, let’s take a look at the application of export default in more complex scenarios. Suppose your component needs some dependencies:

 <code class="javascript">// MyComponent.vue import myMixin from './myMixin.js' export default { name: 'MyComponent', mixins: [myMixin], // ... rest of the component }</code>

Here, we export a component that uses mixin . export default elegantly packs all component details together for easy import and use. This is more concise and easier to understand than using multiple export statements.

Of course, export default is not perfect. If your module needs to export multiple components or functions, export default is not suitable. In this case, you should use the export keyword. Which one to choose depends on your specific needs. Remember that the readability and maintainability of the code are always a priority. Excessive use of export default can cause code to be difficult to understand and maintain.

Finally, regarding performance optimization: export default itself does not have a significant impact on performance. Performance issues usually come from the complexity of the component itself or the unreasonable code writing. Therefore, paying attention to the code quality of components and avoiding unnecessary calculations and DOM operations is the key to improving performance. Remember, clear code is more important than complex optimization techniques.

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