JavaScript Program to Convert Decimal to Binary

In this article, we are going to learn the conversion of numeric values from decimal to binary. Binary is a number system with 2 digits (0 and 1) representing all numeric values.

Given a number N which is in decimal representation. our task is to convert the decimal representation of the number to its equivalent binary representation.

Example 1:

Input : 7
Output : 111

Input : 10
Output : 1010

If the decimal number is 10.

• The remainder when 10 is divided by 2 is zero. Therefore, arr[0] = 0.
• Divide 10 by 2. The new number is 10/2 = 5.
• The remainder when 5 is divided by 2 is 1. Therefore, arr[1] = 1.
• Divide 5 by 2. The new number is 5/2 = 2.
• The remainder, when 2 is divided by 2, is zero. Therefore, arr[2] = 0.
• Divide 2 by 2. The new number is 2/2 = 1.
• The remainder when 1 is divided by 2 is 1. Therefore, arr[3] = 1.
• Divide 1 by 2. The new number is 1/2 = 0.
• Since the number becomes = 0.
• Print the array in reverse order. Therefore the equivalent binary number is 1010.

There are several approaches that can be used to Convert Decimal to Binary, which are listed below:

• Using unsigned right shift operator (>>>)
• Using Loop and String Concatenation
• Using toString(2) Method
• Using Array and Math method

We will explore all the above methods along with their basic implementation with the help of examples.

Approach 1: Using unsigned right shift operator (>>>)

The easiest and most basic way to convert decimal to binary is to use the unsigned right shift operator for converting the input number to an unsigned 32 bit integer. We make use of the toString method with argument 2 to specify that the output should be in base 2 i.e. binary.

Syntax:

function decimalToBinary(N) {
    return (N >>> 0).toString(2);
}

Example: In this example, we are using the above-explained approach.

The binary representation of given number is:- 1010

Approach 2: Using Loop and String Concatenation

In this approach, we use loop and string concatenation

• Initialize an empty string say binary.
• Run a while loop until the decimal number i.e. N is greater than 0.
• Inside the loop find the remainder of N by 2 and concatenate it with a binary string.
• Update the number N after dividing it by 2 in each iteration and use the floor function for it.

Syntax:

while (N > 0) {
    binary = (N % 2) + binary;
    N = Math.floor(N / 2);
}

Example: In this example, we are using the above explained approach.

The binary representation of given number is:- 1010

Approach 3: Using toString(2) Method

The toString(2) method is a built-in JavaScript method available for number objects that converts a numeric value (decimal number) to its binary representation as a string.

Syntax:

num.toString(2)

Example: In this example, we are using the toString(2) method to convert our given numeric value to binary.

Binary representation: 1010

Approach 4: Using Array and Math method

This approach converts a decimal number to binary using an array to store binary digits. It repeatedly divides numbers by 2 and adds remainders to the beginning of the array. The binary representation is then obtained by joining the array elements.

Syntax:

let arr = [];
for (; num1 > 0; num1 = Math.floor(num1 / 2)) {
    arr.unshift(num1 % 2);
}
return arr.join("");

Example: In this example, we are using the above-explained approach.

The binary representation is: 1010