jQuery > plugin > layout element to center

infotown.center.js

/**
*
* layout element to center for targettarget
*
* @param {jQuery} target optional
* @param {String} type optional vertical, horizonal, all
* @return jQuery Object
*/
jQuery.fn.setCenter = function(target, type) {
    target = target || $(window);
    target = (target instanceof jQuery) ? target : $(target);
    if (target.get(0).tagName === 'HTML' || target.get(0).tagName === 'BODY') {
        target = $(window);
    }
    // size
    var width = $(this).width();
    var height = $(this).height();
    // target element size
    var targetWidth = target.width();
    var targetHeight = target.height();
    if (target.get(0) != window) {
        var targetCssPos;
        // target element position
        targetCssPos = target.css('position');
        if ((targetCssPos != 'absolute') && (targetCssPos != 'relative')) {
            target.css({
                position: 'relative'
            });
        }
    }
    // offset
    var offsetX = Math.ceil((targetWidth - width) / 2);
    var offsetY = Math.ceil((targetHeight - height) / 2);
    // type vertical, horizonal, all
    type = type || 'all';
    // position property
    var pos = {
        position: 'absolute'
    };
    if (type == 'vertical' || type == 'all') {
        pos.top = offsetY;
    }
    if (type == 'horizonal' || type == 'all') {
        pos.left = offsetX;
    }
    // layout center
    $(this).css(pos);

    return $(this);
};