in js how to encrypt base 64 code example

Example 1: javascript base64 encode

var string = "Hello folks how are you doing today?";
var encodedString = btoa(string); // Base64 encode the String
var decodedString = atob(encodedString); // Base64 decode the String

Example 2: js base64 encoding

str = "The quick brown fox jumps over the lazy dog";
b64 = btoa(unescape(encodeURIComponent(str)));
str = decodeURIComponent(escape(window.atob(b64)));