What is the usage of alert in javascript
In JavaScript, the usage of alert is "alert (plain text displayed in the dialog box)". The alert method is used to display an alert box with a specified message and an OK button. It can be used to alert the user or debug the program.
The operating environment of this tutorial: windows7 system, javascript version 1.8.5, Dell G3 computer.
alert() method is used to display an alert box with a specified message and an OK button.
Syntax
alert(message)
message refers to the plain text (not HTML text) to be displayed in the dialog box that pops up on the window
Example:
<html>
<head>
<script type="text/javascript">
function disp_alert()
{
alert("我是一个消息框！")
}
</script>
</head>
<body>
<input type="button" onclick="disp_alert()" value="显示消息框" />
</body>
</html>Alert in JS is used to pop up a warning box in the browser.
There are three ways to use alert. Different ways have different effects.
The first way: write directly in the script tag
The code is as follows:
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
<script type="text/javascript">
alert("这是一个警告框");
</script>
</head>
<body>
<p>你看我出不出来</p>；
</body>
</html>The effect is as follows:
<body> <!--将alert编写到onclick属性中，单击后，会弹出警告框--> <button onclick="alert('点，点什么点')">你点我一下</button><br /><br /> <!--将alert写在超链接的href属性中，点击超链接，会弹出警告框--> <a href="javascript:alert('叫你别点，你非要点')">别点我</a><br /> <p>你看我出不出来</p> </body>
alert("这是外部alert");
//重新创建一个js文件，专门用于写alert<script type="text/javascript" src="alert.js">
/*加入src="路径"，可以引入外部alert*/
alert("这是一个警告框");
</script>
javascript advanced tutorial]
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