yarn add js-chacha20

import JSChaCha20 from "js-chacha20";

const key = Uint8Array([...]); // 32 bytes key
const nonce = Uint8Array([...]); // 12 bytes nonce
const message = Uint8Array([...]); // some data as bytes array

// Encrypt //
const encrypt = new JSChaCha20(key, nonce).encrypt(message);

// now encrypt contains bytes array of encrypted message

import JSChaCha20 from "js-chacha20";

const key = Uint8Array([...]); // 32 bytes key
const nonce = Uint8Array([...]); // 12 bytes nonce
const encrypt = Uint8Array([...]); // some data as bytes array

// Encrypt //
const message = new JSChaCha20(key, nonce).decrypt(encrypt);

// now message contains bytes array of original message