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Convert a negative number to positive in JavaScript

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  • Last Updated : 27 Jul, 2022
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We can convert a negative number to a positive number in javascript by the methods described below. 

Method 1: This is a general method in which we will first check whether the number is already positive or negative, if the number is negative then we will multiply the number with -1 to make it positive. Syntax:

if (a < 0) {
    a = a * -1;
}

Example: Below is the implementation of the above approach: 

javascript




<script>
    // Javascript script
    // to convert negative number
    // to positive number
 
    // Function to convert
    // given number to
    // positive number
    function convert_positive(a) {
        // Check the number is negative
        if (a < 0) {
            // Multiply number with -1
            // to make it positive
            a = a * -1;
        }
        // Return the positive number
        return a;
    }
 
//Driver code
var n = -10;
var m = 5;
 
// Call function
n = convert_positive(n);
 
// Print result
document.write(n + "<br>");
 
// Call function
m = convert_positive(m);
 
// Print result
document.write(m + "<br>");
</script>

Output:

10
5

Method 2: In this method we will use Math.abs() function to convert negative number to positive number. Syntax:

Math.abs(value)

Example: Below is the implementation of the above approach: 

javascript




<script>
    // Javascript script
    // to convert negative number
    // to positive number
     
     
    //Driver code
    var n = -30;
    var m = 15;
 
    // Using Math.abs() function
    n = Math.abs(n);
     
    // Print result
    document.write(n + "<br>");
     
    // Using Math.abs() function
    m = Math.abs(m);
     
    // Print result
    document.write(m + "<br>");
</script>                                   

Output:

30
15

Method#3: In this method we will check whether the number is positive or negative, if the number is negative then we add minus sign at the beginning of  number else return same. Syntax:

a < 0 ? -(a) : a

Example:E

Javascript




<script>
        // Javascript script
        // to convert negative number
        // to positive number
 
        // Function to convert
        // given number to
        // positive number
        function convert_positive(a) {
            return a < 0 ? -(a) : a;
        }
     
    //Driver code
    var n = -10;
    var m = 5;
 
    // Call function
    n = convert_positive(n);
 
    // Print result
    console.log(n );
 
    // Call function
    m = convert_positive(m);
 
    // Print result
    console.log(m);
</script>

Output:

10
5

Method#4 : In this method we will use bit-wise  not operator which flip all the bits of number. Since negative number is stored in most significant bit it also flip which convert it to positive number.Syntax: 

a < 0 ? ( ~a + 1 ) : a

Javascript




<script>
        // Javascript script
        // to convert negative number
        // to positive number
 
        // Function to convert
        // given number to
        // positive number
        function convert_positive(a) {
            return a < 0 ? (~a+1) : a;
        }
 
    //Driver code
    var n = -10;
    var m = 5;
 
    // Call function
    n = convert_positive(n);
 
    // Print result
    console.log(n );   
 
    // Call function
    m = convert_positive(m);
 
    // Print result
    console.log(m);
 
</script>

Output:

10 
5

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