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HTML | DOM console.assert( ) Method

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  • Difficulty Level : Basic
  • Last Updated : 13 Jul, 2022
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The console.assert() method in HTML is used to write a message for user on the console only if the expression evaluates to false. The expression and the message are sent as parameters to the console.assert() method. 

Syntax:

console.assert( expression, message )

Parameters: This method accept two parameters as mentioned above and described below:

  • expression: It is a Boolean expression which denotes the message or object to write to the console. It is required parameter.
  • message : It is a string or an object which denotes the message or object to write to the console. It is required parameter.

Below program illustrates the console.assert() method in HTML: 

Example 1: 

html




<!DOCTYPE html>
<html>
    <head>
        <title>DOM console.assert() Method</title>
        <style>
            h1 {
                color:green;
            }
            h2 {
                font-family: Impact;
            }
            body {
                text-align:center;
            }
        </style>
    </head>
    <body>
        <h1>GeeksforGeeks</h1>
        <h2>DOM console.assert() Method</h2>
        <p>To view the message in the console press the F12
        key on your keyboard.</p>
        <script>
            console.assert(document.getElementById("MyElement"),
            "There is no element with the ID 'MyElement'");
        </script>
    </body>
</html>                   


Output:

  
See console view to press F12 Key: 

 

Example 2: Displaying an object while using console.assert() method 

html




<!DOCTYPE html>
<html>
    <head>
        <title>DOM console.assert() Method</title>
        <style>
            h1 {
                color:green;
            }
            h2 {
                font-family: Impact;
            }
            body {
                text-align:center;
            }
        </style>
    </head>
    <body>
        <h1>GeeksforGeeks</h1>
        <h2>DOM console.assert( ) Method</h2>
        <p>To view the message in the console press the F12 key on
             your keyboard.</p>
        <script>
            var MyElement = { Product : "Coca Cola", Type : "Beverage" };
            console.assert(document.getElementById("MyDemo"), MyElement);
        </script>
    </body>
</html>                   


Output:

  
See console view on Pressing the F12 Key: 

 

Supported Browsers: The browser supported by console.assert() method are listed below:

  • Google Chrome 1 and above
  • Edge 12 and above
  • Internet Explorer 8 and above
  • Firefox 28 and above
  • Opera 11 and above
  • Safari 4 and above

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