# \_.mergeWith

**语法：**

```javascript
_.mergeWith(object, sources, customizer)
```

**源代码链接：**[source](https://github.com/lodash/lodash/blob/4.17.10/lodash.js#L13471)

**npm包链接：**[npm package](https://www.npmjs.com/package/lodash.mergewith)

**描述：**

该方法类似[`_.merge`](https://lodash.com/docs/4.17.10#merge)，除了它接受一个`customizer`，调用以产生目标对象和来源对象属性的合并值。如果`customizer`返回`undefined`，将会由合并处理方法代替。`customizer`调用与7个参数：*(objValue, srcValue, key, object, source, stack)*。

> **Note:**这方法会改变对象`object`.

**开始版本：**4.0.0

**参数：**

* `object (Object)`: 目标对象。
* `[sources] (...Object)`: 来源对象。
* `customizer (Function)`: 这个函数定制合并值。

**返回值：**

* `(Object)`: 返回 object。

**例子：**

```javascript
function customizer(objValue, srcValue) {
  if (_.isArray(objValue)) {
    return objValue.concat(srcValue);
  }
}

var object = { 'a': [1], 'b': [2] };
var other = { 'a': [3], 'b': [4] };

_.mergeWith(object, other, customizer);
// => { 'a': [1, 3], 'b': [2, 4] }
```


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