---
layout: page
title: "JavaScript base64_decode function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/base64_decode:357
- /functions/view/base64_decode
- /functions/view/357
- /functions/base64_decode:357
- /functions/357
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's base64_decode

{% codeblock url/base64_decode.js lang:js https://raw.github.com/kvz/phpjs/master/functions/url/base64_decode.js raw on github %}
function base64_decode (data) {
  // From: http://phpjs.org/functions
  // +   original by: Tyler Akins (http://rumkin.com)
  // +   improved by: Thunder.m
  // +      input by: Aman Gupta
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Onno Marsman
  // +   bugfixed by: Pellentesque Malesuada
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +      input by: Brett Zamir (http://brett-zamir.me)
  // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // *     example 1: base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
  // *     returns 1: 'Kevin van Zonneveld'
  // mozilla has this native
  // - but breaks in 2.0.0.12!
  //if (typeof this.window['atob'] === 'function') {
  //    return atob(data);
  //}
  var b64 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
  var o1, o2, o3, h1, h2, h3, h4, bits, i = 0,
    ac = 0,
    dec = "",
    tmp_arr = [];

  if (!data) {
    return data;
  }

  data += '';

  do { // unpack four hexets into three octets using index points in b64
    h1 = b64.indexOf(data.charAt(i++));
    h2 = b64.indexOf(data.charAt(i++));
    h3 = b64.indexOf(data.charAt(i++));
    h4 = b64.indexOf(data.charAt(i++));

    bits = h1 << 18 | h2 << 12 | h3 << 6 | h4;

    o1 = bits >> 16 & 0xff;
    o2 = bits >> 8 & 0xff;
    o3 = bits & 0xff;

    if (h3 == 64) {
      tmp_arr[ac++] = String.fromCharCode(o1);
    } else if (h4 == 64) {
      tmp_arr[ac++] = String.fromCharCode(o1, o2);
    } else {
      tmp_arr[ac++] = String.fromCharCode(o1, o2, o3);
    }
  } while (i < data.length);

  dec = tmp_arr.join('');

  return dec;
}
{% endcodeblock %}

 - [Raw function on GitHub](https://github.com/kvz/phpjs/blob/master/functions/url/base64_decode.js)

Please note that php.js uses JavaScript objects as substitutes for PHP arrays, they are 
the closest match to this hashtable-like data structure. 

Please also note that php.js offers community built functions and goes by the 
[McDonald's Theory](https://medium.com/what-i-learned-building/9216e1c9da7d). We'll put online 
functions that are far from perfect, in the hopes to spark better contributions. 
Do you have one? Then please just: 

 - [Edit on GitHub](https://github.com/kvz/phpjs/edit/master/functions/url/base64_decode.js)

### Example 1
This code
{% codeblock lang:js example %}
base64_decode('S2V2aW4gdmFuIFpvbm5ldmVsZA==');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
'Kevin van Zonneveld'
{% endcodeblock %}


### Other PHP functions in the url extension
{% render_partial _includes/custom/url.html %}