How to convert Number to Boolean in JavaScript ?

Last Updated : 29 Dec, 2023

We convert a Number to Boolean by using the JavaScript Boolean() method and double NOT operator(!!). A JavaScript boolean results in one of two values i.e. true or false. However, if one wants to convert a variable that stores integer “0” or “1” into Boolean Value i.e. “false” or “true”.

Below are the approaches:

Table of Content

Boolean() method
Using double NOT(!!) operator

Approach 1: Boolean() method

The boolean function returns the boolean value of the variable. It can also be used to find the boolean result of a condition, expression, etc

Syntax:

Boolean(variable/expression)

Example: This example converts a number into a boolean.

HTML

<!DOCTYPE html>
<html>
<body>
    <center>
        <h1 style="color:green">
            GeeksforGeeks
        </h1>
 
        <h4>
            Click the button to change the
            number value into boolean.
        </h4>
 
        <button onclick="myFunction()">Change</button>
 
        <p>The number value of the variable is :</p>
 
        <p id="result"></p>
 
        <script>
            // Initializing boolvalue as true 
            let numvalue = 1;
             
            // JavaScript program to illustrate boolean 
            // conversion using ternary operator 
            function myFunction() {
             
                document.getElementById("result")
                    .innerHTML = Boolean(numvalue);
            } 
        </script>
    </center>
</body>
</html>

Note: If the above Boolean() method is called as Boolean(!numvalue), it shows the result as “false“. Similarly, if it is called Boolean(!!numvalue), it gives the result as “true“.

Output:

Approach 2: Using double NOT(!!) operator

This operator converts numbers with the value of zero to false and all other numbers to true.

Example: In this example, we will use the double NOT operator to convert the number into a boolean value.

HTML

<!DOCTYPE html>
<html>
<body>
    <center>
        <h1 style="color:green">
            GeeksforGeeks
        </h1>
 
        <h4>
            Click the button to change the
            number value into boolean.
        </h4>
 
        <button onclick="myFunction()">Change</button>
 
        <p>The number value of the variable is :</p>
 
        <p id="result"></p>
 
        <script>
            // Initializing boolvalue as true
            let numvalue = (!!1)
 
            // JavaScript program to illustrate boolean
            // conversion using ternary operator
            function myFunction() {
 
                document.getElementById("result")
                    .innerHTML = (numvalue);
            }
        </script>
    </center>
</body>
</html>