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Javascript Hex To Decimal: Javascript Explained

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When working with colors, data manipulation, or mathematical calculations in JavaScript, there often arises a need to convert values from hexadecimal (hex) format to decimal. In this article, we will explore various methods to perform this conversion seamlessly.

The process is fairly straightforward, but there are a few important points and coding challenges one must keep in mind when working with hex to decimal conversion in JavaScript.

Let’s get started!

Understanding Hexadecimal Numbers

Understanding hex is the first step in writing a Javascript program for hex to decimal conversion. Hex numbers are four-digit representations of integers and are a common way to shorten calculations and programming scripts. Hexadecimal is numbered 0-9 and then A-F. Every number can be represented by a set of sixteen digits and four hexadecimal digits describe a single byte. For example, the hex number FF translates to the decimal number 255.

Hexadecimal numbers are often used in computing because they are easier to read and understand than binary numbers. Hexadecimal numbers are also used in HTML and CSS coding to represent colors. By using hexadecimal numbers, web developers can create a wide range of colors for their websites. Hexadecimal numbers are also used in cryptography to encrypt data and protect it from unauthorized access.

Decoding Hexadecimal to Decimal

Decoding hexadecimal to decimal is a formulaic process. To convert hexadecimal to decimal, one must first convert the hex number into binary form and then convert the binary form back to decimal. To convert binary numbers to decimal, one multiplies each bit (0 or 1) by two raised to the power of its location. The ones (1) add up and result in the decimal equivalent of the original hex number.

It is important to note that the hexadecimal number system is base 16, while the decimal number system is base 10. This means that each digit in a hexadecimal number is worth 16 times more than the digit in the same position in a decimal number. For example, the hexadecimal number “A” is equal to 10 in decimal, while the hexadecimal number “F” is equal to 15 in decimal.

Using Javascript to Convert Hex to Decimal

Using Javascript for hex to decimal conversion not only allows users to quickly understand numbers represented in hex, but it also reduces the amount of time it takes to write long, complex scripts. There are a few different ways to write JavaScript code to perform a hex to decimal conversion. One of the more straightforward approaches is to use the built-in parseInt() function as shown below.

Another approach is to use the bitwise operators to convert the hexadecimal number to its decimal equivalent. This approach is more efficient than the parseInt() function, as it requires fewer lines of code. However, it is also more complex and requires a deeper understanding of bitwise operations.

JavaScript Hex to Decimal Code

The built-in parseInt() function can be used to easily convert a hexadecimal value into a decimal value in JavaScript. This can be done by passing in two parameters: the string representation of the hex number as the first parameter, and 16 as the second parameter. The 16 tells JavaScript that 16 is the base of the numbers passed in. The parseInt() function returns a numerical value that is equivalent to the hex value.

let hexValue = '1a';
let decimalValue = parseInt(hexValue, 16);
console.log(decimalValue); // Outputs: 26

It is important to note that the parseInt() function will only work with strings that contain valid hexadecimal characters. If the string contains any other characters, the function will return NaN (Not a Number). Additionally, the parseInt() function will only return the integer portion of the hexadecimal value, so any fractional portion of the value will be discarded.

Custom Function for JS Hex to Decimal

If you’re keen on understanding the underlying process, or if you’re looking for a “js hex to dec” solution without library methods, you can write a custom function:

function hexToDecimal(hexString) {
    let decimal = 0;
    let base = 1; // Start from the least significant digit

    for(let i = hexString.length - 1; i >= 0; i--) {
        let currentDigit = hexString[i];

        if (currentDigit >= '0' && currentDigit <= '9') {
            decimal += (currentDigit - '0') * base;
        } else if (currentDigit >= 'a' && currentDigit <= 'f') {
            decimal += (currentDigit.charCodeAt(0) - 87) * base; // 'a' is 97 in ASCII
        } else if (currentDigit >= 'A' && currentDigit <= 'F') {
            decimal += (currentDigit.charCodeAt(0) - 55) * base; // 'A' is 65 in ASCII

        base *= 16;

    return decimal;

console.log(hexToDecimal('1a')); // Outputs: 26

This function manually computes the decimal equivalent by multiplying each hex digit by the power of 16 corresponding to its position.

Working with Big Integers and Floats

Keep in mind that the parseInt() function is primarily designed for integers. To convert large or floating-point numbers like 0x100000.22, you’ll need to employ custom JavaScript code. This customization involves two primary steps:

  1. Separate the given number into its integer and fractional components.
  2. Utilize the parseInt() function to obtain the decimal equivalent of the integer portion.

For the fractional segment, calculate the equivalent decimal value by multiplying each hexadecimal digit with 16 raised to its corresponding position.

It’s worth noting that the parseInt() function inherently handles 32-bit integers. For handling larger numbers, consider using a library like BigInteger.js. This library enables manipulation and conversion of large integers and floating-point numbers with a suite of versatile functions.

Decoding Binary and Octal With Javascript

The parseInt() function also works for octal (base 8) and binary (base 2) numbers conversion. All you have to do is pass in 8 or 2 as the second parameter and you will get the decimal equivalent for octal or binary numbers.

For example, if you want to convert the binary number 1101 to decimal, you can use the parseInt() function like this: parseInt(1101, 2). This will return the decimal equivalent of 13.

Advantages of Using Javascript for Conversion

Using Javascript for hex to decimal conversion provides some advantages over other programming languages. Firstly, it is not necessary to use cumbersome external libraries or write complex algorithms like C++ or Python. Secondly, because Javascript is a dynamically typed language, it can convert hexadecimals with varying lengths, which is especially useful when working with large integers or floats. Finally, numeric conversion in Javascript is fast and efficient.

In addition, Javascript is a cross-platform language, meaning it can be used on multiple operating systems and devices. This makes it an ideal choice for web development, as it can be used to create applications that can be accessed from any device. Furthermore, Javascript is a relatively easy language to learn, making it a great choice for beginners who are just starting out with programming.

Tips for Writing Efficient Hex to Decimal Scripts

When writing scripts for hexadecimal to decimal conversion in Javascript, it is important to consider performance and efficiency. Minimizing the number of loops, using constants for constant operations, caching values and storing results in variables all help enhance performance. Additionally, using built-in functions and libraries can reduce code size and therefore improve performance.

It is also important to consider the readability of the code. Using descriptive variable names, comments, and indentation can make the code easier to read and understand. This can help reduce the time needed to debug and maintain the code in the future.

Troubleshooting Common Errors

Javascript is an easy language to learn, but there are still some common errors that may appear when writing hexadecimal to decimal conversion scripts. Make sure that you are always passing in the correct parameters when calling functions and make sure that you are accounting for large integers and floats. Additionally, make sure that you are properly validating input strings so they are not longer than they should be.

Hexadecimal to decimal conversion in Javascript is a straightforward process that involves understanding hexadecimal numbers, decoding them into decimal numbers, and writing efficient scripts that use built-in functions. Knowing how to troubleshoot errors and following a few best practices can help improve efficiency when writing scripts. Hopefully this article has provided enough information to help you write effective hexadecimal to decimal conversion scripts in Javascript.

It is also important to remember that hexadecimal to decimal conversion is not the only type of conversion that can be done in Javascript. There are many other types of conversions that can be done, such as binary to decimal, octal to decimal, and decimal to binary. Understanding the basics of each type of conversion can help you write more efficient scripts and make sure that you are getting the correct results.

Error Messages:

It’s crucial to familiarize oneself with prevalent JavaScript error messages that surface during these conversions. Such knowledge can assist in pinpointing the root of issues. For instance, outputs like NaN often signal incorrect or non-numerical inputs during conversions.

Wrapping Up

Whether you’re using native JavaScript functions or crafting your own solution, converting values from “hex to decimal javascript” or “js hex to decimal” is an essential tool in your JavaScript arsenal. Remember, always choose a method that aligns with the requirements and constraints of your specific project. Whether it’s for color manipulation, data handling, or other applications, knowing how to “convert hex to decimal js” can greatly streamline your coding processes.

Nisha Kumari

Nisha Kumari

Nisha Kumari, a Founding Engineer at Bito, brings a comprehensive background in software engineering, specializing in Java/J2EE, PHP, HTML, CSS, JavaScript, and web development. Her career highlights include significant roles at Accenture, where she led end-to-end project deliveries and application maintenance, and at PubMatic, where she honed her skills in online advertising and optimization. Nisha's expertise spans across SAP HANA development, project management, and technical specification, making her a versatile and skilled contributor to the tech industry.

Written by developers for developers

This article was handcrafted with by the Bito team.

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