# 5.2 事件物件(Event Object)

## 認識事件物件

任何的事件發生時，都會隨附一個事件物件(Event Object)，它會提供的額外資訊，依照事件類型的不同，會帶有不同的資料。

## 基本事件寫法

```javascript
var my_el = document.getElementById("abc");
my_el.addEventListener("click", function(){
  
});
```

如果在某些情境當中，需要使用到事件物件，那就可以帶入函式的第一個參數，例：

```javascript
var my_el = document.getElementById("abc");
my_el.addEventListener("click", function(e){ // e 就是 event object
  console.log(e); // 將 e 印在 console 中看
});
```

## 範例：取得鍵盤按下的 ASCII Code 碼

透過 **`e.which`** 來取得 keyup 事件發生時的 ASCII Code 碼：

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

參考：[w3schools Event Object](https://www.w3schools.com/JSREF/obj_event.asp)。(看看網址裡面的，找一下 `e.target` 是什麼？)


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