Base64 Decoding In JavaScript

Base64 is a binary-to-text encoding system that converts binary data into radix-64 representations, which are then encoded as ASCII strings. It is frequently used to store data in files and send data over the internet. JavaScript provides native functions and modules for encoding and decoding Base64 data.

This article discusses how to decode Base64 data in JavaScript, covering the following topics:

1. What is Base64?
2. How to decode Base64 data in JavaScript using built-in functions
3. How to decode Base64 data in JavaScript using a third-party library
4. Best practices for using Base64 in JavaScript

1. What is Base64?

A Javascript binary-to-text encoding system called Base64 displays binary data as ASCII strings. In order to accomplish this task, the binary data is converted into a representation known as radix-64, which consists of 64 characters. These characters include the 26 uppercase and lowercase letters of the English alphabet, the 10 numerals, and two extra characters that vary depending on the implementation. If the final data block is less than 6 bits, it is padded with zeros to ensure that it is a full 6 bits in length.

Base64 uses 6 bits per character to represent binary data. Each chunk of data is represented by a character from the Base64 character set, divided into six-bit chunks and encoded in Base64. Whenever the last chunk of data is less than six bits, it is padded with zeros to make it a full six bits.

Base64 is commonly used for transmitting data over the internet and storing data in files. For example, it is used in email attachments, HTML images, and JSON Web Tokens (JWTs).

2. How to decode Base64 data in JavaScript using built-in functions

Using JavaScript’s built-in functions, such as atob(), you can easily decode Base64 data. Atob() takes a Base64-encoded string as input and returns the decoded binary data.

Here is an example of how to use atob() to decode Base64 data:

const base64String = 'SGVsbG8gV29ybGQh'; // Base64-encoded string  
constdecodedString = atob(base64String); // Decoded string  
console.log(decodedString); // Output: "Hello World!"  

We begin with the Base64-encoded string SGVsbG8gV29ybGQh, which represents the string “Hello World!”. This string is passed to the atob() function, which returns the decoded binary data as a string. After that, we log the decoded string to the console.

Note that the atob() function only works with ASCII strings. It may be necessary to use a third-party library if the Base64-encoded data contains non-ASCII characters.

3. How to decode Base64 data in JavaScript using a third-party library

There are different third-party libraries available for decoding Base64 data in JavaScript. Js-base64 provides a comprehensive Base64 API with support for Unicode and other encodings.

To use js-base64, you first need to install it using a package manager, such as npm:

npm install js-base64  

Once installed, you can use the library to decode Base64 data as follows:

const base64 = require('js-base64');  
const base64String = 'SGVsbG8gV29ybGQh'; // Base64-encoded string  
constdecodedString = base64.decode(base64String); // Decoded string  
console.log(decodedString); // Output: "Hello World!"  

In this example, we first import the js-base64 library using require() function.

4. Best practices for using Base64 in JavaScript:

There are several practices for using Base64 in JavaScript, including:

1. Use Base64 for encoding binary data

Javascript Base64 encodes binary data, such as images, audio, and video. It’s not intended for encoding text data, such as JSON or HTML.

2. Use third-party libraries for advanced features

It is recommended that you use a third-party library if you need to work with Unicode or other character encodings, or if you need to handle large amounts of data. Js-base64 and base64-js are two popular Base64 libraries for JavaScript.

3. Be aware of security risks

By itself, Base64 encoding does not provide any security. As a result, you should avoid encoding sensitive data using Base64, and you should always use encryption to protect your data.

4. Test thoroughly

If you are working with Base64 data, it is important that you test your code thoroughly to ensure that it is functioning correctly. In order to ensure that your code is robust and reliable, you should test for edge cases, such as large data sets, non-ASCII characters, and unexpected input.