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74 lines
1.3 KiB
JavaScript
74 lines
1.3 KiB
JavaScript
---
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title: 02-数据的赋值
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publish: true
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---
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<ArticleTopAd></ArticleTopAd>
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## 对象赋值
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### 用 Object.assgin() 实现浅拷贝
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代码举例：
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```js
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const obj1 = {
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name: 'qianguyihao',
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age: 28,
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desc: 'hello world',
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};
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const obj2 = {
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name: '许嵩',
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sex: '男',
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};
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// 【关键代码】浅拷贝：把 obj1 赋值给 obj2。这行代码的返回值也是 obj2
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Object.assign(obj2, obj1);
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console.log(JSON.stringify(obj2));
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```
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打印结果：
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```
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{
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"name":"qianguyihao",
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"sex":"男",
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"age":28,
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"desc":"hello world"
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}
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```
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注意，**上面这行代码在实际开发中，会经常遇到，一定要掌握**。它的作用是：将 obj1 的值追加到 obj2 中。如果两个对象里的属性名相同，则 obj2 中的值会被 obj1 中的值覆盖。
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## 数组赋值
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### 扩展运算符
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```js
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arr2 = arr1;
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```
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上方代码中，其实是让 arr2 指向 arr1 的地址。也就是说，二者指向的是同一个内存地址。
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如果不想让 arr1 和 arr2 指向同一个内存地址，我们可以借助扩展运算符来做：
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```javascript
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let arr2 = [...arr1]; //arr2 会开辟新的内存地址
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```
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参考链接：
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- [javaScript中浅拷贝和深拷贝的实现](https://github.com/wengjq/Blog/issues/3)
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