Can't define array element

Question

I can't make this little thing work. Don't know what's the problem, but my array elements can't get defined, alert always gives me back NaN. Tried to alert the jQuery selectors, they're working perfectly. What's the problem?

        var sldr                                = $("#slider img"),
            count                           = sldr.length-1,
            containerHeight         = $("#slider").css('height'),
            images                          = new Array(),
            imgHeights                  = new Array(),
            imgWidths                       = new Array(),
            imgSlices                       = new Array(),
            choosenSlice                =   '',
            slicer                          = '';


        var i=0;
        for (i=0;i<=count;i++){
            images[i]               = $("#slider img:eq("+i+")");
            imgHeights[i]       = $("#slider img:eq("+i+")").attr('height');
            imgWidths[i]        = $("#slider img:eq("+i+")").attr('width');
            imgSlices[i]        = (Math.round(imgHeights[i]/containerHeight))-1;
            alert(imgSlices[i]);
        }

Zach · Accepted Answer · 2011-10-19 23:21:52Z

3

If the 'height' or 'width' attribute isn't set on one of the images, or isn't a number, then trying to divide with it might result in a NaN result.

Try converting those values to a number using parseInt:

mgHeights[i]       = parseInt($("#slider img:eq("+i+")").attr('height'));
imgWidths[i]       = parseInt($("#slider img:eq("+i+")").attr('width'));

answered Oct 19, 2011 at 23:21

Zach

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3 Comments

wintercounter Over a year ago

Thanks, it worked. But why i can't store other than numbers? codeimages[i]=$("#slider img:eq("+i+")");code this will be an object for example... And they are set in the <img> tag... can't understand...

Zach Over a year ago

You can store things other than numbers, but doing math with them will result in NaN. Attributes on the tag like height and width ultimately are strings -- they might just be string representations of numbers, but they are still a string type. It sounds like what might be happening is that even if you set a width of "400", the browser might interpret it as "400px". The extra non-number characters are probably preventing it from being treated as a number without parsing.

Zach Over a year ago

Just to clarify, the real issue here is division of strings (on the next line), and that is solved by storing numbers instead of strings for the values used in the division. In general, you can store whatever you want in an array.

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