---
layout: page
title: "JavaScript include_once function"
comments: true
sharing: true
footer: true
alias:
- /functions/view/include_once:434
- /functions/view/include_once
- /functions/view/434
- /functions/include_once:434
- /functions/434
---
<!-- Generated by Rakefile:build -->
A JavaScript equivalent of PHP's include_once

{% codeblock language/include_once.js lang:js https://raw.github.com/kvz/phpjs/master/functions/language/include_once.js raw on github %}
function include_once (filename) {
  // http://kevin.vanzonneveld.net
  // +   original by: Legaev Andrey
  // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   improved by: Michael White (http://getsprink.com)
  // +      input by: Brett Zamir (http://brett-zamir.me)
  // +   bugfixed by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
  // +   bugfixed by: Brett Zamir (http://brett-zamir.me)
  // -    depends on: include
  // %        note 1: Uses global: php_js to keep track of included files (though private static variable in namespaced version)
  // *     example 1: include_once('http://www.phpjs.org/js/phpjs/_supporters/pj_test_supportfile_2.js');
  // *     returns 1: true
  var cur_file = {};
  cur_file[this.window.location.href] = 1;

  // BEGIN STATIC
  try { // We can't try to access on window, since it might not exist in some environments, and if we use "this.window"
    //    we risk adding another copy if different window objects are associated with the namespaced object
    php_js_shared; // Will be private static variable in namespaced version or global in non-namespaced
    //   version since we wish to share this across all instances
  } catch (e) {
    php_js_shared = {};
  }
  // END STATIC
  if (!php_js_shared.includes) {
    php_js_shared.includes = cur_file;
  }
  if (!php_js_shared.includes[filename]) {
    if (this.include(filename)) {
      return true;
    }
  } else {
    return true;
  }
  return false;
}
{% endcodeblock %}

 - [view on github](https://github.com/kvz/phpjs/blob/master/functions/language/include_once.js)
 - [edit on github](https://github.com/kvz/phpjs/edit/master/functions/language/include_once.js)

### Example 1
This code
{% codeblock lang:js example %}
include_once('http://www.phpjs.org/js/phpjs/_supporters/pj_test_supportfile_2.js');
{% endcodeblock %}

Should return
{% codeblock lang:js returns %}
true
{% endcodeblock %}


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