# 5.9 練習

## 練習：內容展開縮合

先認識 scrollHeight：指的是某一個區塊裡面的內容高度。例：

寫法：

```javascript
var block_el = document.getElementById("block");
console.log(block_el.scrollHeight); // 區塊裡面的內容高度
```

{% embed url="<https://codepen.io/carlos411/pen/qBVVoZW>" %}

再來看內容的展開縮合：

{% embed url="<https://codepen.io/carlos411/pen/zYPPjWN>" %}

另外附上 jQuery 語法範例：<https://codepen.io/carlos411/pen/poLroKg>


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