# mixin

混入 (mixin) 提供了一种非常灵活的方式，来分发 Vue 组件中的可复用功能。

## 组件混入

```javascript
// 定义一个混入对象
var myMixin = {
  created: function () {
    this.hello()
  },
  methods: {
    hello: function () {
      console.log('hello from mixin!')
    }
  }
}

// 定义一个使用混入对象的组件
var Component = Vue.extend({
  mixins: [myMixin]
})

var component = new Component() // => "hello from mixin!"
```

## 全局混入

```javascript
// 为自定义的选项 'myOption' 注入一个处理器。
Vue.mixin({
  created: function () {
    var myOption = this.$options.myOption
    if (myOption) {
      console.log(myOption)
    }
  }
})

new Vue({
  myOption: 'hello!'
})
// => "hello!"
```

## 合并策略

当组件和混入对象含有同名选项时，这些选项将以恰当的方式进行“合并”。比如，数据对象在内部会进行递归合并，并在发生冲突时以组件数据优先。

同名钩子函数（created, mounted, desctroyed) 将合并为一个数组，因此都将被调用。另外，混入对象的钩子将在组件自身钩子**之前**调用。

值为对象的选项，例如 `methods`、`components` 和 `directives`，将被合并为同一个对象。两个对象键名冲突时，取组件对象的键值对。


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