# 作用域

```javascript
var color = "blue"; 
function changeColor(){ 
  if (color === "blue"){ 
  color = "red"; 
  } else { 
  color = "blue"; 
  } 
} 
changeColor(); 
alert("Color is now " + color);
```

## 特殊情况

- if
- for
- ...

> 垃圾回收 gc