The Node btoa() and atob() functions are the only ones that have been deprecated. However, if you're working on the DOM code (front-end) and see this deprecated notice, you can use the window object to get around it.

window.atob()

For more info

Still within VS Code, I had a look into the comments for the deprecated btoa(str) function. It suggests the following as a replacement:

const base64Str = Buffer.from(str, 'utf8').toString('base64');

btoa(): accepts a string where each character represents an 8bit byte. If you pass a string containing characters that cannot be represented in 8 bits, it will probably break. Probably that's why btoa is deprecated.

atob(): returns a string where each character represents an 8-bit byte.

If you are using nodejs just replace atob and btoa with Buffer. Here is the official documentation Buffers in nodejs:

//With NodeJS

export const encodeBase64 = (data) => {
    return Buffer.from(data).toString('base64');
}
export const decodeBase64 = (data) => {
    return Buffer.from(data, 'base64').toString('ascii');
}

Otherwise, you could install buffer with "yarn add buffer" or "npm i buffer" to run on browser. The buffer module's API is identical to node's Buffer API.

Here is a React sample using javascript module to browser, but it can run on any modern javascript frontend app that uses webpack or parcel or even vanilla javascript with script src:

//this will run on browser    
import React from "react";
import { Buffer } from 'buffer';
export default function App() {

  const encodeBase64 = (data) => {
    return Buffer.from(data).toString('base64');
  }
  const decodeBase64 = (data) => {
    return Buffer.from(data, 'base64').toString('ascii');
  }

  return <div>
    {'encoded test to base64 = ' + encodeBase64('test')}<br />
    {'decoded dGVzdA== to ascII = ' + decodeBase64('dGVzdA==')}
  </div>;
}

The above react hook will result:

encoded test to base64 = dGVzdA==
decoded dGVzdA== to ascII = test