Position by center point, rather than top-left point

Question

Is it possible to tell the code to position by the center point of an element, rather than by the top-left point? If my parent element has

width         


        

Answer 1

left:50% doesn't center the center of gravity of this div 50% to the left, it is the distance between the left border and the left border of the parent element, so basically you need to do some calculations.

left = Width(parent div) - [ Width(child div) + Width(left border) + Width(right border) ]

left = left / 2

So you can do a Javascript function...

function Position(var parentWidth, var childWith, var borderWidth)
{
      //Example parentWidth = 400, childWidth = 200, borderWidth = 1
      var left = (parentWidth - ( childWidth + borderWidth));
      left = left/2;
      document.getElementById("myDiv").style.left= left+"px";
}