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HTML | DOM console.assert( ) Method

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:



<!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

<!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
  • Apple Safari
  • Firefox 28.0
  • Opera
  • Internet Explorer


This article is attributed to GeeksforGeeks.org

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