jquery.position.js

jquery.position.js

jQuery.fn.extend({
        position: function() {
                if ( !this[0] ) {
                        return null;
                }

                var elem = this[0],

                // Get *real* offsetParent
                offsetParent = this.offsetParent(),

                // Get correct offsets
                offset       = this.offset(),
                parentOffset = /^body|html$/i.test(offsetParent[0].nodeName) ? { top: 0, left: 0 } : offsetParent.offset();

                // Subtract element margins
                // note: when an element has margin: auto the offsetLeft and marginLeft
                // are the same in Safari causing offset.left to incorrectly be 0
                offset.top  -= parseFloat( jQuery.curCSS(elem, "marginTop",  true) ) || 0;
                offset.left -= parseFloat( jQuery.curCSS(elem, "marginLeft", true) ) || 0;

                // Add offsetParent borders
                parentOffset.top  += parseFloat( jQuery.curCSS(offsetParent[0], "borderTopWidth",  true) ) || 0;
                parentOffset.left += parseFloat( jQuery.curCSS(offsetParent[0], "borderLeftWidth", true) ) || 0;

                // Subtract the two offsets
                return {
                        top:  offset.top  - parentOffset.top,
                        left: offset.left - parentOffset.left
                };
        },

        offsetParent: function() {
                return this.map(function() {
                        var offsetParent = this.offsetParent || document.body;
                        while ( offsetParent && (!/^body|html$/i.test(offsetParent.nodeName) && jQuery.css(offsetParent, "position") === "static") ) {
                                offsetParent = offsetParent.offsetParent;
                        }
                        return offsetParent;
                });
        }
});