function json_decode (str_json) { 
    var json = this.window.JSON;
    if (typeof json === 'object' && typeof json.parse === 'function') {
        try {
            return json.parse(str_json);
        } catch(err) {
            if (!(err instanceof SyntaxError)) {
                throw new Error('Unexpected error type in json_decode()');
            }
            this.php_js = this.php_js || {};
            this.php_js.last_error_json = 4; // usable by json_last_error()
            return null;
        } 
    }    
    var cx = /[\u0000\u00ad\u0600-\u0604\u070f\u17b4\u17b5\u200c-\u200f\u2028-\u202f\u2060-\u206f\ufeff\ufff0-\uffff]/g;
    var j;
    var text = str_json;
    cx.lastIndex = 0;
    if (cx.test(text)) {
        text = text.replace(cx, function (a) {
            return '\\u' +
            ('0000' + a.charCodeAt(0).toString(16)).slice(-4);
        });
    }
    if ((/^[\],:{}\s]*$/).
        test(text.replace(/\\(?:["\\\/bfnrt]|u[0-9a-fA-F]{4})/g, '@').
            replace(/"[^"\\\n\r]*"|true|false|null|-?\d+(?:\.\d*)?(?:[eE][+\-]?\d+)?/g, ']').
            replace(/(?:^|:|,)(?:\s*\[)+/g, ''))) {
        j = eval('(' + text + ')'); 
        return j;
    }
 
    this.php_js = this.php_js || {};
    this.php_js.last_error_json = 4; // usable by json_last_error()
    return null;
}