Collection of pure JS functions to get an element's center point

getElementCenter.js

function getElementCenter(elem) {

	var props = elem.getBoundingClientRect(),
		x = 0,
		y = 0;

	//Calculating X
	if (props.left > props.right) 
		x = (props.left - props.right)/2 + props.right;
	else if (props.left < props.right) 
		x = (props.right - props.left)/2 + props.left
	else x=props.left;

	//Calculating Y
	if (props.top > props.bottom) 
		y = (props.top > props.bottom)/2 + props.bottom;
	else if (props.top < props.bottom)
		y = (props.bottom - props.top)/2 + props.top
	else
		y=props.top;

	return {x: x, y: y}
}

function getElementOffsetCenter(elem) {

	var	x = 0,
		y = 0,
		ontop,
		topoffset = 0;

	//Calculating X
	x = elem.offsetWidth / 2 + elem.offsetLeft;
	
	//Calculating Y
	y = elem.offsetHeight / 2 + elem.offsetTop;
	
	if (elem.offsetParent) {
		parent = elem;
		while (parent.offsetParent) { 
			 topoffset += parent.offsetTop;
			 if (parent.offsetParent) { parent = parent.offsetParent; }
			 else break;
		}
		
		y = elem.offsetHeight / 2 +topoffset; 
	}
	

	return {x: x, y: y}
}

function placeDotInCenter(elem) {
	var dot = document.createElement('span'),
		points = getElementCenter(elem);

	dot.setAttribute('style', 'position: absolute; display: block; z-index:9999999999; width: 5px; height: 5px; background: red; top: '+(points.y)+'px; left: '+(points.x)+'px;');

	document.body.appendChild(dot);

	window.addEventListener('scroll', updatePosition, false);
	window.addEventListener('resize', updatePosition, false);

	function updatePosition() {
		points = getElementCenter(elem);
		dot.setAttribute('style', 'position: absolute; display: block; z-index:99999999999; width: 5px; height: 5px; background: red; top: '+(points.y)+'px; left: '+(points.x)+'px;');
	}

}

function placeDotInOffsetCenter(elem) {
	var dot = document.createElement('span'),
		points = getElementOffsetCenter(elem);

	dot.setAttribute('style', 'position: absolute; display: block; z-index:9999999999999; width: 5px; height: 5px; background: red; top: '+(points.y)+'px; left: '+(points.x)+'px;');

	document.body.appendChild(dot);

	window.addEventListener('scroll', updatePosition, false);
	window.addEventListener('resize', updatePosition, false);

	function updatePosition() {
		points = getElementOffsetCenter(elem);
		dot.setAttribute('style', 'position: absolute; display: block; z-index:9999999999999; width: 5px; height: 5px; background: red; top: '+(points.y)+'px; left: '+(points.x)+'px;');
	}

}