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HTML DOM Window alert() Method

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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:

jiu

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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