Question

I have these two functions.

The first is well written because someone who knows how to write js did it.

The second I did.

var GetURLParameter = function($param){
    var sPageURL = window.location.search.substring(1);
    var sURLVariables = sPageURL.split('&');
    for(var i = 0; i < sURLVariables.length; i++) {
        var sParameterName = sURLVariables[i].split('=');
        if (sParameterName[0] == $param) {
            return sParameterName[1];
        }
    }
}


if(GetURLParameter('filter')!= "undefined"){
     $('#'+GetURLParameter('filter')).parent().parent().children('li.active').removeClass('active')
     $('#'+GetURLParameter('filter')).parent().addClass('active');
}

I would like to simplify the calls as I’m repeating the line GetURLParameter('filter') but I don’t know how I can make it work like the key word this

Answer 1

Just stash the intermediate values in variables:

var $filter = GetURLParameter('filter');

if($filter != "undefined") { 
    var $parent = $('#' + GetURLParameter('filter')).parent();

    $parent.parent().children('li.active').removeClass('active');
    // better alternative (thanks wirey)
    // $parent.siblings('li.active').removeClass('active')

    $parent.addClass('active');
}

Of course this has the advantage of being more readable, and also it’s more efficient because it doesn’t re-rerun the same function or query the DOM multiple times.