function changeUrlArg(url, arg, val){
var pattern = arg+‘=([^&]*)‘;
var replaceText = arg+‘=‘+val;
return url.match(pattern) ? url.replace(eval(‘/(‘+ arg+‘=)([^&]*)/gi‘), replaceText) : (url.match(‘[\?]‘) ? url+‘&‘+replaceText : url+‘?‘+replaceText);
}
