function CenterInsideDiv(divContainer,elementToCenter) {
            var divContainerHeight = divContainer.height();
            var elementToCenterHeight = elementToCenter.outerHeight();

            var elementNewTop = divContainerHeight / 2 - elementToCenterHeight / 2;

            elementToCenter.css({ top: elementNewTop, left: 0 });                            
        }   

// call function like this
CenterInsideDiv($("#elementToCenterId").parent(), $("#elementToCenterId"));

Position of the element to center needs to be relative to the container.

Center element inside of a div container

center

JavaScript