# 4.4 更新節點

## 屬性

### .setAttribute() 或 點語法(dot syntax)

任何屬性都可以透過 `.setAttribute()` 來更新；或者有些有些可以透過 「點語法(dot syntax)」。

需帶入兩個參數：

* 第一個：欲更新的屬性名稱。
* 第二個：欲設定的值。

```javascript
var para = document.getElementById("para1");
para.setAttribute("style", "color: red;");
```

假設有個按鈕，點擊後，狀態變成 **`disabled`**：

```javascript
var btn = document.getElementById("btn");
btn.addEventListener("click", function(){
  
  this.disabled = true;
});
```

例：

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

## 內容

### .innerHTML

更新元素裡的全部內容，原內容會整個被清空。\
然後更新的內容中，如果有 HTML 相關原始碼的話，會當做 HTML 來看待。

例：

```javascript
var para = document.getElementById("para1");
para.innerHTML = "<strong>新的文字</strong>";
```

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

### .innerText

更新元素裡的全部內容，原內容會整個被清空。\
然後更新的內容中，如果有 HTML 相關原始碼的話，會當做 **純文字** 來看待。

例：

```javascript
var para = document.getElementById("para1");
para.innerText = "<strong>新的文字</strong>";
```

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


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