function include_once(filename) 
{
    // *     example 1: include_once('http://www.phpjs.org/js/phpjs/_supporters/pj_test_supportfile_2.js');
    // *     returns 1: true
    var cur_file = {};
    cur_file[window.location.href] = 1;

    if (!window.php_js) window.php_js = {};
    if (!window.php_js.includes) window.php_js.includes = cur_file;
    if (!window.php_js.includes[filename]) {
        if (include(filename)) {
            return true;
        }
    } else {
        return true;
    }
}

function include(filename) 
{
    // %        note 1: Force Javascript execution to pause until the file is loaded. Usually causes failure if the file never loads. ( Use sparingly! )
    // %        note 2: The included file does not come available until a second script block, so typically use this in the header.
    // *     example 1: include('http://www.phpjs.org/js/phpjs/_supporters/pj_test_supportfile_2.js');
    // *     returns 1: 1
    var js = document.createElement('script');
    js.setAttribute('type', 'text/javascript');
    js.setAttribute('src', filename);
    js.setAttribute('defer', 'defer');
    document.getElementsByTagName('HEAD')[0].appendChild(js);

    // save include state for reference by include_once
    var cur_file = {};
    cur_file[window.location.href] = 1;

    if (!window.php_js) window.php_js = {};
    if (!window.php_js.includes) window.php_js.includes = cur_file;
    if (!window.php_js.includes[filename]) {
        window.php_js.includes[filename] = 1;
    } else {
        window.php_js.includes[filename]++;
    }

    return window.php_js.includes[filename];
}