Function siblingCheck

2.0.3/Sizzle.js:369–390

* Checks document order of two siblings * @param {Element} a * @param {Element} b * @returns {Number} Returns less than 0 if a precedes b, greater than 0 if a follows b

(a, b)

         */

        function siblingCheck(a, b) {
            var cur = b && a,
                diff = cur && a.nodeType === 1 && b.nodeType === 1 &&
                    (~b.sourceIndex || MAX_NEGATIVE) -
                    (~a.sourceIndex || MAX_NEGATIVE);

            // Use IE sourceIndex if available on both nodes
            if (diff) {
                return diff;
            }

            // Check if b follows a
            if (cur) {
                while ((cur = cur.nextSibling)) {
                    if (cur === b) {
                        return -1;
                    }
                }
            }

            return a ? 1 : -1;
        }

        /**
         * Returns a function to use in pseudos for input types