Converting String to Uint8Array & Vice-Versa in Javascript

Here are the ways to convert a string to Uint8Array and vice-versa:

Converting String to Uint8Array

1. Using TextEncoder

const str = 'Hello, World!';
const encoder = new TextEncoder();
const uint8Array = encoder.encode(str);

2. Using charCodeAt() and Uint8Array constructor

const str = 'Hello, World!';
const uint8Array = new Uint8Array(str.length);
for (let i = 0; i < str.length; i++) {
  uint8Array[i] = str.charCodeAt(i);
}

3. Using charCodeAt() and Array.prototype.map()

const str = 'Hello, World!';
const uint8Array = Array.prototype.map.call(str, (c) => c.charCodeAt(0));

4. Using Buffer (Node.js only)

const str = 'Hello, World!';
const uint8Array = Buffer.from(str, 'utf-8');

5. Using ArrayBuffer and DataView

const str = 'Hello, World!';
const arrayBuffer = new ArrayBuffer(str.length);
const dataView = new DataView(arrayBuffer);
for (let i = 0; i < str.length; i++) {
  dataView.setUint8(i, str.charCodeAt(i));
}
const uint8Array = new Uint8Array(arrayBuffer);

6. Using charCodeAt and for loop

// Convert string to Uint8Array manually
function stringToUint8Array(str) {
    const uint8Array = new Uint8Array(str.length);
    for (let i = 0; i < str.length; i++) {
        uint8Array[i] = str.charCodeAt(i);
    }
    return uint8Array;
}

const str = "Hello, World!";
const uint8ArrayManual = stringToUint8Array(str);
console.log(uint8ArrayManual); // Output: Uint8Array(13) [72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]

7. Using split() and map()

const str = 'Hello, World!';
const uint8Array = str.split('').map((c) => c.charCodeAt(0));

Converting Uint8Array to String

1. Using TextDecoder

const uint8Array = new Uint8Array([72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]);
const decoder = new TextDecoder();
const str = decoder.decode(uint8Array);

2. Using String.fromCharCode() and Array.prototype.map()

const uint8Array = new Uint8Array([72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]);
const str = Array.prototype.map.call(uint8Array, (c) => String.fromCharCode(c)).join('');

3. Using Buffer (Node.js only)

const uint8Array = new Uint8Array([72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]);
const str = Buffer.from(uint8Array).toString('utf-8');

4. Using DataView and ArrayBuffer

const uint8Array = new Uint8Array([72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]);
const arrayBuffer = uint8Array.buffer;
const dataView = new DataView(arrayBuffer);
const str = '';
for (let i = 0; i < uint8Array.length; i++) {
  str += String.fromCharCode(dataView.getUint8(i));
}

5. Using Array.prototype.reduce()

const uint8Array = new Uint8Array([72, 101, 108, 108, 111, 44, 32, 87, 111, 114, 108, 100, 33]);
const str = uint8Array.reduce((acc, c) => acc + String.fromCharCode(c), '');