getCoordinate of any box in JS

getCoordinate.js

var getCoordinate = function(elemId, parentId){

    var element = document.getElementById(elemId);
    var context = document.getElementById(parentId);

    var bodyRect = context.getBoundingClientRect(),
        pointPos = element.getBoundingClientRect(),
        offsetY   = pointPos.top - bodyRect.top;
        offsetX   = pointPos.left - bodyRect.left;
        centerX = offsetX + pointPos.width / 2;
        centerY = offsetY + pointPos.height / 2;

        return {
            height: pointPos.height,
            width: pointPos.width,
            x: centerX, 
            y: centerY
        };
}