How to use export default and import in Vue

export default is used to export Vue components and allow other modules to access. import is used to import components from other modules, which can import a single or multiple components.

export default and import in Vue: a delicate component combination

Many beginners are confused by export default and import in Vue components, thinking that they are like a pair of indistinguishable twins and are always unable to figure out who is who. In fact, the key to understanding them lies in understanding the idea of ​​modularity of Vue components. Let’s discuss this article in depth so that you can fully grasp them.

Let's talk about the conclusion first: export default is used to export a Vue component, while import is used to import this component and use it elsewhere. Simple? But there are many ways here.

Basics: Modularity and Components

In Vue, we advocate component development, splitting complex pages into small, reusable components. export default and import are the key to achieving component modularization. Imagine that if all the code is piled in one file without them, it would be a disaster to maintain!

export default : the export of the component

The purpose of the export default statement is to export a Vue component so that other modules can access it. It only allows exporting one default component. See an example:

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

This code defines a component named MyComponent and exports it using export default . Note that there is only one export here, which is the export default feature.

import : the component's entry

The purpose of the import statement is to import components from other modules. It can import a single component or multiple components. Let's see how to import MyComponent defined above:

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

Here, we import MyComponent from './MyComponent.vue' to import MyComponent component from the MyComponent.vue file. Then, register the component in the components option, and finally render it with <mycomponent></mycomponent> in the template. Isn't it very simple?

Advanced usage and potential problems

You might be wondering, what if I have multiple components to export? At this time, you can use the export statement instead of export default . export allows you to export multiple named components, but requires the corresponding name when importing. This will be more flexible in large projects, but also adds management complexity.

A common mistake is to forget to register imported components in the components option. If you forget to register, Vue will not recognize the component, resulting in rendering failure. When debugging, double check your components options to make sure all imported components are registered correctly.

Furthermore, the correctness of the path is crucial. Make sure the path in your import statement is correct, otherwise an error that the module cannot find will occur. Both relative or absolute paths are OK, but keep consistency.

Performance optimization

In large projects, a large number of component imports may affect performance. You might consider using on-demand loading or code segmentation techniques to optimize loading speeds. These techniques are beyond the scope of this article, but they are worth exploring after you have studied Vue in depth.

In short, export default and import are the cornerstones of Vue components modularity, and understanding them is the key to writing high-quality Vue applications. Remember, they work together, export default is responsible for export, import is responsible for import, both are indispensable. Practice more and practice more and you can easily control them!

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