HTML | DOM Input Checkbox required Property

Difficulty Level : Basic
Last Updated : 11 Mar, 2019

The Input Checkbox required property in HTML DOM is used to set or return whether the input checkbox field should be checked or not before submitting the form. This property is used to reflect the HTML required attribute.

Syntax:

It returns the Input Checkbox required property.
```
checkboxObject.required
```
It is used to set the Input Checkbox required property.
```
checkboxObject.required = true|false
```

Property Values: It contains two property values which are listed below:

true: It is used to specify the checkbox must be checked before submitting the form.
false: It has a default value. It specifies that the checkbox must not be checked before submitting the form.

Return Value: It returns a Boolean value which represents the checkbox must be checked or not before submitting the form.

Example 1: This example returns the Input Checkbox required property.

<!DOCTYPE html> 
<html>  
    <head>  
        <title> 
            DOM Input Checkbox required Property 
        </title> 
    </head>  
      
    <body style = "text-align: center;">  
      
        <h1 style = "color: green;"> 
            GeeksforGeeks 
        </h1>  
          
        <h2>DOM Input Checkbox required Property</h2>  
          
        <form >  
          
            <!-- Below input elements have attribute "required" -->
            <input type="checkbox" name="check" id="GFG"
                    value="1" required>Checked by default<br>  
                      
            <input type="checkbox" name="check" value="2"> 
                    Not checked by default<br>  
        </form> <br> 
          
        <button onclick="myGeeks()"> 
            Submit 
        </button> 
          
        <p id="sudo" style="color:green;font-size:30px;"></p> 
          
        <!-- Script to use required property -->
        <script> 
            function myGeeks() { 
                var g = document.getElementById("GFG").required; 
                document.getElementById("sudo").innerHTML = g; 
            } 
        </script> 
    </body>  
</html>                     

Output:
Before clicking on the Button:

After clicking on the Button:

Example 2: This example sets the Input Checkbox required property.

<!DOCTYPE html> 
<html>  
    <head>  
        <title> 
            DOM Input Checkbox required Property 
        </title> 
    </head>  
      
    <body style = "text-align: center;">  
      
        <h1 style = "color: green;"> 
            GeeksforGeeks 
        </h1>  
          
        <h2>DOM Input Checkbox required Property</h2> 
          
        <form >  
            <!-- Below input elements have attribute 
                    "required" -->
            <input type="checkbox" name="check" id="GFG"
                    value="1" required>Checked by default<br>  
                      
            <input type="checkbox" name="check" value="2"> 
                    Not checked by default<br>  
        </form> <br> 
          
        <button onclick="myGeeks()"> 
            Submit 
        </button> 
          
        <p id="sudo" style="color:green;font-size:20px;"></p> 
          
        <!-- Script to set Input Checkbox required Property -->
        <script> 
            function myGeeks() { 
                var g = document.getElementById("GFG").required 
                        = "false"; 
                          
                document.getElementById("sudo").innerHTML 
                        = "The value of the required attribute" 
                          + " was changed to " + g; 
            } 
        </script> 
    </body>  
</html>                     

Output:
Before clicking on the button:

After clicking on the button:

Supported Browsers: The browser supported by DOM input Checkbox required Property are listed below:

Google Chrome
Internet Explorer 10.0
Firefox
Opera
Safari

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