js parse 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: javascript base64 decode

var decodedString = atob(encodedString);

Example 3: javascript base64url decode

var decode = function(input) {
        // Replace non-url compatible chars with base64 standard chars
        input = input
            .replace(/-/g, '+')
            .replace(/_/g, '/');

        // Pad out with standard base64 required padding characters
        var pad = input.length % 4;
        if(pad) {
          if(pad === 1) {
            throw new Error('InvalidLengthError: Input base64url string is the wrong length to determine padding');
          }
          input += new Array(5-pad).join('=');
        }

        return input;
    }