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Vue3 Api Extends
## Vue 3 `extends` API
In Vue 3, the `extends` option is a powerful feature that allows one component to inherit and extend the options of another.
By using `extends`, you can reuse and customize existing component logic without duplicating code. This is highly beneficial for reducing code redundancy and improving the overall maintainability of your codebase.
---
## Common Use Cases
The `extends` option is typically used in the following scenarios:
1. **Reusing Component Logic**: When you have a base component and other components need to inherit its core logic.
2. **Customizing Component Behavior**: When you need to inherit from a base component but override or customize specific behaviors.
3. **Building Configurable Components**: Constructing highly flexible and configurable components through inheritance and extension.
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## Basic Syntax
```javascript
import BaseComponent from './BaseComponent.vue';
export default {
extends: BaseComponent,
// Add new options here or override existing options from BaseComponent
};
```
In the code snippet above, the component inherits from `BaseComponent` using the `extends` property. You can then add new options or override existing options defined in `BaseComponent`.
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## Code Examples
### 1. The Base Component
First, let's define a base component named `BaseComponent.vue`:
```html
```
### 2. The Extended Component
Next, we create a new component named `ExtendedComponent.vue` that inherits from `BaseComponent` and overrides the `message` data property:
```html
```
In this example, `ExtendedComponent` inherits all the logic from `BaseComponent` but overrides the `message` property. As a result, the rendered output will display: **"Hello from ExtendedComponent!"**.
---
## Key Considerations & Best Practices
When using the `extends` option, keep the following rules in mind:
### 1. Option Merging Strategy
When a component extends another, Vue performs an option-merging process:
* **Object-based options** (such as `data`, `methods`, `computed`, and `watch`) undergo a shallow merge. If there is a naming conflict, the child component's properties will override those of the parent component.
* **Data properties** are recursively merged. The child component's data properties take precedence in case of conflicts.
### 2. Lifecycle Hooks Execution Order
If both the parent (extended) component and the child component define the same lifecycle hooks (e.g., `created`, `mounted`), **both** hook functions will be called.
* The parent component's hook is executed **first**, followed by the child component's hook.
### 3. Template Inheritance
The `extends` option **only inherits the JavaScript logic** of the component. It does not inherit the `` or `