查看当前节点的前后兄弟元素节点

Element.prototype.getElementSibling = function (n) {let node = this,type = typeof(n);if (type === 'undefined' && type !== 'number') {return;}while (n) {if (n > 0) { // 控制往前找还是往后找node = node.nextElementSibling;n--;} else if (n < 0) {node = node.previousElementSibling;n++;}}return node;
}