How to Convert Byte Array to String in JavaScript ?

A Byte array is an array containing encoded data in the form of unsigned integers. It can’t be used directly. We have to decode it to get the meaning full data out of it. In this article, we will learn the conversion of a given byte array to a string of characters.

Various approaches to convert byte array to string are as follows:

Approach 1: Using WebAPI TextDecoder.decode() Method

The decode() method in TextDecoder API is used to take a stream of bytes as input and emit a stream of code points. The TextEncoder decode() method takes an ArrayBuffer containing the encoded data and options object and returns the original string (i.e. decoded string).

Syntax:

decoder.decode( buffer, options );

Parameters:

• buffer: It is an ArrayBuffer, Dataview, or TypedArray instance that contains the encoded data.
• options: It is an optional parameter that holds an object containing some properties. 
  • stream: It is a boolean value. It is set to true if data are processing in chunks and false if data are not chunked (by default its value is set to false)

Return Value:

 It decodes the encoded input in the buffer and returns the decoded string.

Example: In this example, we will create a string using the TextDecoder.decode() method from the Uint8Array instance.

Javascript

// Creating new byte array using
// Uint8Array instance
let byteArray = new Uint8Array([
    74, 97, 118, 97, 83, 99, 114, 105, 112, 116,
]);

// Creating textDecoder instance
let decoder = new TextDecoder("utf-8");

// Using decode method to get string output
let str = decoder.decode(byteArray);

// Display the output
console.log(str);

Output

JavaScript

Approach 2: Using Buffer and toString() Methods

Buffers are instances of the Buffer class in Node.js. Buffers are designed to handle binary raw data.

Syntax:

let arr = new Buffer([16, 32, 48, 64]);

The JavaScript Array toString() Method returns the string representation of the array elements

Syntax:

arr.toString();

Example: In this example, we have implemented the Buffer and toString() Methods for converting the byte array to a String.

Javascript

// Creating new input array buffer
let byteArray = Buffer.from([
    74, 97, 118, 97, 83, 99, 114, 105, 112, 116,
]);

// Converting buffer to string
let str = byteArray.toString();

// Display output
console.log(str);

Output

JavaScript

Approach 3: Using JavaScript string.fromCharCode() Method

The JavaScript string.fromCharCode() method is used to create a string from the given sequence.

Syntax:

String.fromCharCode(n1, n2, ..., nX);

Example: In this example, we will use String.fromCharCode() method to get the string output from a given byteArray.

Javascript

// Input byte Array for
let byteArray = [
    71, 101, 101, 107, 115, 102, 111,
    114, 71, 101, 101, 107, 115,
];

// Iterating array using array.map method
let str = byteArray
    .map((byte) => {
        return String.fromCharCode(byte);
    })
    .join("");

// Dipslay the output
console.log(str);

Output

GeeksforGeeks