file_exists

function file_exists (url) {
    // Returns true if filename exists  
    // 
    // version: 909.322
    // discuss at: http://phpjs.org/functions/file_exists    // +   original by: Enrique Gonzalez
    // +      input by: Jani Hartikainen
    // +   improved by: Kevin van Zonneveld (http://kevin.vanzonneveld.net)
    // %        note 1: This function uses XmlHttpRequest and cannot retrieve resource from different domain.
    // %        note 1: Synchronous so may lock up browser, mainly here for study purposes.     // *     example 1: file_exists('http://kevin.vanzonneveld.net/pj_test_supportfile_1.htm');
    // *     returns 1: '123'
 
    var req = this.window.ActiveXObject ? new ActiveXObject("Microsoft.XMLHTTP") : new XMLHttpRequest();
    if (!req) {throw new Error('XMLHttpRequest not supported');}      
    // HEAD Results are usually shorter (faster) than GET
    req.open('HEAD', url, false);
    req.send(null);
    if (req.status == 200){        return true;
    }
 
    return false;
}