Convert a number to a hex string in JavaScript

This post will discuss how to convert a number to a hex string in JavaScript.

To convert a number to a hex string in JavaScript, we can use one of the following functions:

1. Using `Number.toString()` function

We can use the Number.toString() function of the number object, which takes a base as an argument and returns the string representation of the number in that base. We can pass 16 as the base argument to get the hexadecimal representation of the number. This method works for both positive and negative numbers. For example, we can convert a number to a hex string using toString() like this:

let num = 1000;

let str = num.toString(16);

// str is "3e8"

console.log(str);

Download Run Code

We can use it with the padStart() function of the string object to add the prefix to the hex string if needed. The padStart() function pads a string with another string until it reaches a certain length. For example, to convert a positive number 100 to a hex string with prefix "0x":

let num = 100;

let hexString = num.toString(16);

hexString = hexString.padStart(hexString.length + 2, "0x");

// hexString is "0x64"

console.log(hexString);

Download Run Code

Alternatively, we can use the + operator to add a prefix to the hex string. For example, we can convert a positive number to a hex string with prefix "0x" using + like this:

let num = 1000;

let hexString = "0x" + num.toString(16);

// hexString is "0x3e8"

console.log(hexString);

Download Run Code

2. Using bitwise operators

We can use the bitwise operators to manipulate the bits of the number and extract the hex digits. For example, we can use the right shift operator (>>) to divide the number by 16 and get the remainder, which is the last hex digit. Then we can use the bitwise AND operator (&) to mask out the last four bits of the number and repeat the process until we get all the hex digits. We can use a lookup table to map each hex digit to its corresponding character. This method works for both positive and negative numbers. For example:

let num = 500;

let hexString = "";

let hexDigits = "0123456789ABCDEF";

while (num > 0)

{

// get the last hex digit and prepend it to the hex string

hexString = hexDigits[num & 15] + hexString;

// right shift by 4 bits (divide by 16)

num = num >> 4;

}

// hexString is "1F4"

console.log(hexString);

Download Run Code

3. Using `BigInt` object

Another option is to convert the number to the BigInt value, and use the toString() function of the BigInt object with a radix of 16 to convert it to a hexadecimal string. This will handle negative numbers correctly, but it requires a modern browser that supports BigInt. For example:

let num = 500;

// create a BigInt object from a number

let bigNum = BigInt(num);

// get the hexadecimal string using the toString function

let hexString = bigNum.toString(16);

// hexString is "1f4"

console.log(hexString);

Download Run Code

That’s all about converting a number to a hex string in JavaScript.

Convert a number to a hex string in JavaScript

1. Using Number.toString() function

2. Using bitwise operators

3. Using BigInt object

Share this:

1. Using `Number.toString()` function

3. Using `BigInt` object