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HTML Window alert() method is used to display an alert box. It displays a specified message along with an OK button and is generally used to make sure that the information comes through the user. It returns a string that represents the text to display in the alert box.
Note: Alert boxes grab your attention and make you read a message and Using too many alerts stops you from doing other things on the webpage until you close them.
Syntax:
alert(message);Parameter:
Message: It is the message that is needed to show in the alert box and it’s optional.
Example: Display an alert box by double-clicking a button.
html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<h1 style="color: green;">
GeeksforGeeks
</h1>
<p>
For displaying the alert message, double
click the "Show Alert Message" button:
</p>
<button ondblclick="myalert()">
Show Alert Message
</button>
<script>
function myalert() {
alert("Welcome to GeeksforGeeks.\n " +
"It is the best portal for computer" +
"science enthusiasts!");
}
</script>
</body>
</html>
Output:
Example: Alert the hostname of the current URL
HTML
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport"
content="width=device-width, initial-scale=1.0">
<title>Alert Hostname Example</title>
</head>
<body style="text-align: center;">
<h1 style="color: green;">
Geeks
</h1>
<p>
To see the hostname of the current URL,
click the "Show Hostname" button:
</p>
<button onclick="showHostname()">
Show Hostname
</button>
<script>
function showHostname() {
let currentURL = window.location.hostname;
alert("The hostname of the current URL is: " + currentURL);
}
</script>
</body>
</html>
Output:
Supported Browsers:
- Google Chrome 1
- Edge 12
- Firefox 1
- Opera 3
- Safari 1
We have a Cheat Sheet on Javascript where we covered all the important topics of Javascript to check those please go through Javascript Cheat Sheet-A Basic guide to JavaScript.
Last Updated : 16 Jan, 2024
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