层次的级别有：parent/children/sibling。
父节点
父节点遍历方法有：$.fn.parent(), $.fn.parents(), $.fn.parentsUntil(), and $.fn.closest().示例如下：
<div class="grandparent"> <div class="parent"> <div class="child"> <span class="subchild"></span> </div> </div> <div class="surrogateParent1"></div> <div class="surrogateParent2"></div> </div>
// Selecting an element's direct parent // returns [ div.child ] $("span.subchild").parent(); // Selecting all the parents of an element that match a given selector // returns [ div.parent ] $("span.subchild").parents("div.parent"); // returns [ div.child, div.parent, div.grandparent ] $("span.subchild").parents(); // Selecting all the parents of an element up to, but *not including* the selector // returns [ div.child, div.parent ] $("span.subchild").parentsUntil("div.grandparent"); // Selecting the closest parent, note that only one parent will be selected // and that the initial element itself is included in the search // returns [ div.child ] $("span.subchild").closest("div"); // returns [ div.child ] as the selector is also included in the search $("div.child").closest("div");
子节点
子节点的遍历方法有：$.fn.children() and $.fn.find()。
$.fn.children()只找直接子节点，$.fn.find()迭代遍历所有的子节点。示例如下：
// Selecting an element's direct children // returns [ div.parent, div.surrogateParent1, div.surrogateParent2 ] $("div.grandparent").children("div"); // Finding all elements within a selection that match the selector // returns [ div.child, div.parent, div.surrogateParent1, div.surrogateParent2 ] $("div.grandparent").find("div");
兄弟节点
遍历兄弟节点的基本方法有：$.fn.prev()；$.fn.next()；$.fn.siblings()；$.fn.nextAll()；.fn.nextUntil(), $.fn.prevAll() and $.fn.prevUntil().
示例如下：
// Selecting a next sibling of the selectors // returns [ div.surrogateParent1 ] $("div.parent").next(); // Selecting a prev sibling of the selectors // returns [] as No sibling exists before div.parent $("div.parent").prev(); // Selecting all the next siblings of the selector // returns [ div.surrogateParent1, div.surrogateParent2 ] $("div.parent").nextAll(); // returns [ div.surrogateParent1 ] $("div.parent").nextAll().first(); // returns [ div.surrogateParent2 ] $("div.parent").nextAll().last(); // Selecting all the previous siblings of the selector // returns [ div.surrogateParent1, div.parent ] $("div.surrogateParent2").prevAll(); // returns [ div.surrogateParent1 ] $("div.surrogateParent2").prevAll().first(); // returns [ div.parent ] $("div.surrogateParent2").prevAll().last();
$.fn.siblings()选择所有的兄弟节点：
// Selecting an element's siblings in both directions that matches the given selector // returns [ div.surrogateParent1, div.surrogateParent2 ] $("div.parent").siblings(); // returns [ div.parent, div.surrogateParent2 ] $("div.surrogateParent1").siblings();
