base64 encode in javascript and decode in php

PHP
base64_decode('base64');<?php 
  
// Program to illustrate base64_decode() 
// function 
$str = 'R0ZHLCBBIGNvbXB1dGVyIFNjaWVuY2UgUG9ydGFsIEZvciBHZWVrcw'; 
echo base64_decode($str). "\n"; 
  
$str = 'MQ=='; 
echo base64_decode($str). "\n"; 
?> 

Source

Also in PHP: