Question

I use the following code to check whether or not a certain div exists. And if it doesn’t it adds it to the dom in the proper place.

if (!($("#col"+lastSlide).length))
{
    $('#schDisplay').prepend('<div id="col' + (lastSlide) + '"></div>');
}

My problem is that when this if statement checks again for a div that had already once been appended/prepended, it doesn’t see the div that I added. So it will continue to add the div that was already prepended/appended.

Is there any way this issue can be fixed?

more code:

//fillin added column
function fillElement(colnum)
{
    var URL = 'schedule.php';
    $("#col"+colnum).text("Loading...").show();
    $.post(URL,{fecolnum: colnum}, 
    function (data)
    {
        $("#col"+colnum).html(data).show();
    });
}
//...irrelevant code...

    // Create event listeners for .arrows clicks
      $('.arrows')
        .bind('click', function(){
            numberOfSlides++;
            // Determine new position
            if ($(this).attr('id')=='arrow_right')
            {
                lastSlide++;
                currentPosition++;
                if (!($("#col"+lastSlide).length))
                {
                    $('#schDisplay').append('<div id="col' + lastSlide + '" class="schColumn" style="float: left; width: ' +slideWidth+ 'px"></div>');
                    fillElement(lastSlide);
                }
            }
            else
            {
                lastSlide--;
                currentPosition--;
                if (!($("#col"+lastSlide-2).length))
                {
                    $('#schDisplay').prepend('<div id="col' + (lastSlide-2) + '" class="schColumn" style="float: left; width: ' +slideWidth+ 'px"></div>');
                    fillElement(lastSlide-2);
                }
            }

Answer 1

I don’t have much context to go off of, but checkout this jsfiddle I made from what you gave me.

Notice the line where I’ve made a comment that you can comment out the increment statement. Basically, this is how you can test what happens when “lastSlide” is the same value. (versus if “lastSlide” is indeed a different value).

You might just try debugging your actual code and make sure that lastSlide has the value you actually expect.