Javascript - Getting CSS width and height values

function getCSS(element, property) {
  var elem = document.getElementById(element);
  var css = null;
  if(elem.currentStyle) {
    css = elem.currentStyle[property];
  } else if(window.getComputedStyle) {
     css = document.defaultView.getComputedStyle(elem, null).getPropertyValue(property);
  }
return css;
}

var width = getCSS('test', 'width');
var height = getCSS('test', 'height');
  
alert(parseInt(width)); // 100
alert(parseInt(height)); // 100