> For the complete documentation index, see [llms.txt](https://docs.webmix.cc/javascript/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.webmix.cc/javascript/4.-javascript-chang-yong-nei-jian-han-shi/4.9-this-keyword.md).

# 4.9 this 關鍵字

在 `javascript/practice` 資料夾下，建立 `this.html` 檔案，以便練習。

## 範例1

```javascript
//"use strict";
console.log(this); // window
```

```javascript
"use strict";
console.log(this); // window
```

## 範例2

```javascript
//"use strict";

function test(){
  console.log(this); // window
}
test();
```

```javascript
"use strict";

function test(){
  console.log(this); // undefined
}
test();
```

## 範例3

```javascript
//"use strict";

var myobj = {
  data: "my_str",
  test: function(){
    console.log(this); // myobj
  }
};

myobj.test();
```

```javascript
"use strict";

var myobj = {
  data: "my_str",
  test: function(){
    console.log(this); // myobj
  }
};

myobj.test();
```