# 声明提升相关

输出是什么

```javascript
var num = 8
var num = 10

console.log(num)
```

{% tabs %}
{% tab title="选项" %}

* A: `8`
* B: `10`
* C: `SyntaxError`
* D: `ReferenceError`
  {% endtab %}

{% tab title="答案" %}
**答案: B**

使用 `var` 关键字，你可以用相同的名称声明多个变量。然后变量将保存最新的值。

你不能使用 `let` 或 `const` 来实现这一点，因为它们是块作用域的。
{% endtab %}
{% endtabs %}


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