Javascript find closest number in array without going under

Question

I have an array of numbers, for example [300, 500, 700, 1000, 2000, 3000] and I want to find the closest number, without going under the number given.

F

Answer 1

 sizesAvailable.sort(function(a, b){return a-b});  // DESCENDING sort

if(upscaleImages)   // do th eif once, not every time through the loop
{
    $.each(sizesAvailable, function()
    {  
        if (this > monitorWidth) 
            sizeToUse = this;
    }
    if (sizeToUse == null) sizeToUse = sizesAvailable[0];
}
else
{
    $.each(sizesAvailable, function()
    {  
        //We don't want to upscale images so....
    }
 }
});