Convert a negative number to positive in JavaScript

In JavaScript, a negative number can be converted to its positive equivalent using arithmetic operations or built-in methods.

• Multiplying a negative number by -1 converts it to positive.
• Math.abs() directly returns the absolute value of a number.
• The unary minus (-) operator can be used to change the sign of a negative number.
• Bitwise operations can also convert negative integers, but they are less suitable for general-purpose number handling.
• Math.sqrt() with Math.pow() can obtain the positive magnitude of a number.

Approach 1: Using the Multiplication Operator (*)

A negative number can be converted to a positive number by multiplying it by -1. Before multiplying, check whether the number is negative to avoid changing an already positive number.

Working:

• Check whether the number is less than 0.
• If it is negative, multiply it by -1.
• Return the resulting positive number.

Syntax:

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

function convertToPositive(number) {
    if (number < 0) {
        number = number * -1;
    }

    return number;
}

const number1 = -10;
const number2 = 5;

console.log(convertToPositive(number1));
console.log(convertToPositive(number2));

10
5

Approach 2: Using the Math.abs() Method

The Math.abs() method returns the absolute value of a number. Therefore, it can be used to convert a negative number into its positive equivalent.

Working:

• Pass the number to Math.abs().
• If the number is negative, its positive equivalent is returned.
• If the number is already positive, it remains unchanged.

Syntax:

Math.abs(number)

const number1 = -30;
const number2 = 15;

console.log(Math.abs(number1));
console.log(Math.abs(number2));

30
15

Approach 3: Using the Unary Minus (-) Operator

The unary minus operator can be used to change the sign of a number. By checking whether the number is negative, we can negate it only when necessary.

Syntax:

number < 0 ? -number : number

function convertToPositive(number) {
    return number < 0 ? -number : number;
}

const number1 = -10;
const number2 = 5;

console.log(convertToPositive(number1));
console.log(convertToPositive(number2));

10
5

Approach 4: Using Bitwise Operators

The bitwise NOT (~) operator can be used with +1 to obtain the positive equivalent of a negative integer. This works because JavaScript represents bitwise operands as signed 32-bit integers.

Syntax: 

number < 0 ? ~number + 1 : number

function convertToPositive(number) {
    return number < 0 ? ~number + 1 : number;
}

const number1 = -10;
const number2 = 5;

console.log(convertToPositive(number1));
console.log(convertToPositive(number2));

10
5

Note: Bitwise operators convert their operands to signed 32-bit integers, so this approach is not recommended for general-purpose numbers, especially numbers outside the 32-bit integer range.

Approach 5: Using Math.sqrt() and Math.pow()

The Math.pow() method can square a number, making the result positive. Then, Math.sqrt() can be used to obtain its positive square root.

Working:

• Square the number using Math.pow(number, 2).
• The squared value is always non-negative.
• Use Math.sqrt() to obtain the positive magnitude.

Syntax:

Math.sqrt(Math.pow(number, 2))

function convertToPositive(number) {
    return Math.sqrt(Math.pow(number, 2));
}

const negativeNumber = -5;

console.log(convertToPositive(negativeNumber));

5

Note: For simply converting a number to its positive equivalent, Math.abs() is the most direct and recommended approach.