102 lines
1.9 KiB
Markdown
102 lines
1.9 KiB
Markdown
|
---
|
|||
|
title: Where to
|
|||
|
localeTitle: 去哪儿
|
|||
|
---
|
|||
|
## 去哪儿
|
|||
|
|
|||
|
JavaScript是HTML和Web的编程语言。在HTML中,必须在`<script>`容器标记中插入JavaScript。
|
|||
|
|
|||
|
### 例
|
|||
|
|
|||
|
```html
|
|||
|
|
|||
|
<script>
|
|||
|
window.alert("This JavaScript Works!");
|
|||
|
</script>
|
|||
|
```
|
|||
|
|
|||
|
另外,请记住,您可以在HTML文档中放置任意数量的`<script>`标记。
|
|||
|
|
|||
|
### `<script>`标签在哪里?
|
|||
|
|
|||
|
`<script>`标记可以放在`<head>`或`<body>` 。
|
|||
|
|
|||
|
### `<head>` JavaScript
|
|||
|
|
|||
|
在此示例中,JavaScript放在文档的`<head>`部分中。创建一个**onClicked**函数,在按下按钮时调用该函数。
|
|||
|
|
|||
|
```html
|
|||
|
|
|||
|
<!DOCTYPE html>
|
|||
|
<html>
|
|||
|
<head>
|
|||
|
<script>
|
|||
|
function onClicked() {
|
|||
|
window.alert("Hi, there!");
|
|||
|
}
|
|||
|
</script>
|
|||
|
</head>
|
|||
|
|
|||
|
<body>
|
|||
|
|
|||
|
<h1>JavaScript Testing</h1>
|
|||
|
<button type="button" onclick="onClicked()">Try it</button>
|
|||
|
|
|||
|
</body>
|
|||
|
</html>
|
|||
|
```
|
|||
|
|
|||
|
### `<body>` JavaScript
|
|||
|
|
|||
|
这里,JavaScript放在 。创建了**onClicked**函数,并将其设置为在单击按钮时触发。
|
|||
|
|
|||
|
```html
|
|||
|
|
|||
|
<!DOCTYPE html>
|
|||
|
<html>
|
|||
|
<body>
|
|||
|
|
|||
|
<h1>JavaScript Testing</h1>
|
|||
|
<button type="button" id="buttonClicked">Try it</button>
|
|||
|
|
|||
|
<script>
|
|||
|
document.getElementById("buttonClicked").onclick = onClicked;
|
|||
|
|
|||
|
function onClicked() {
|
|||
|
window.alert("Hi, there!");
|
|||
|
}
|
|||
|
</script>
|
|||
|
|
|||
|
</body>
|
|||
|
</html>
|
|||
|
```
|
|||
|
|
|||
|
### 外部脚本
|
|||
|
|
|||
|
脚本也可以放在外部文件中。让我们创建一个文件**script.js** 。
|
|||
|
|
|||
|
##### 的script.js
|
|||
|
|
|||
|
```javascript
|
|||
|
window.alert("Hi!");
|
|||
|
```
|
|||
|
|
|||
|
此脚本可以包含在HTML文档中,如下所示:
|
|||
|
|
|||
|
```html
|
|||
|
|
|||
|
<!DOCTYPE html>
|
|||
|
<html>
|
|||
|
<body>
|
|||
|
|
|||
|
<script src="script.js"></script>
|
|||
|
|
|||
|
</body>
|
|||
|
</html>
|
|||
|
```
|
|||
|
|
|||
|
_嗨!_在呈现页面时仍会收到警报。请记住,您不需要在JavaScript文件(扩展名为**.js**的文件)中包含`<script>`标记。
|
|||
|
|
|||
|
#### 更多信息:
|
|||
|
|
|||
|
雅虎建议在底部放置脚本。这阐述了[这里](https://developer.yahoo.com/performance/rules.html#js_bottom) ,与这一建议的原因。
|