How to get the position of an element in its parent element with jquery

jQuery is a popular JavaScript library that is often used to handle HTML and CSS related operations. When using jQuery for DOM manipulation, a common need is to get the position of an element within its parent element. This article will show you how to use jQuery to get the position of an element within its parent element.

First of all, we need to understand the index() method in jQuery and its usage and purpose. index() The method is used to return the index value of an element in its sibling nodes. For example, we have the following HTML structure:

<ul>
  <li>Item 1</li>
  <li>Item 2</li>
  <li>Item 3</li>
</ul>

We want to get the index value of the second <li> element in its sibling node. We can use the following jQuery code:

var index = $("li:eq(1)").index();
console.log(index); // 输出 1

The above code means that we first use the selector $("li:eq(1)") to select the second <li> element, and then Then call the index() method to get the index value of the element in its sibling nodes. Since this element is the second sibling, its index is 1.

However, what if we want to get the position of an element in its parent element instead of its sibling node? At this time we need to use a combination of the three methods parent(), children() and index() to achieve this goal. The following is a specific example:

<ul>
  <li>Item 1</li>
  <li class="selected">Item 2</li>
  <li>Item 3</li>
  <li>Item 4</li>
</ul>

In the above HTML structure, we have a <ul> element, which contains four <li> element. One of the <li> elements has a selected class to identify it as the selected element. We want to know the position of the selected <li> element in its parent element.

We can use the following jQuery code to achieve this:

var selectedLi = $("li.selected");
var parentUl = selectedLi.parent();
var index = parentUl.children("li").index(selectedLi);
console.log(index); // 输出 1

The above code first uses the selector $ ("li.selected") to select items with selected class's <li> element, and then use the parent() method to get its parent element <ul>. Next, we use the children("li") method to get all the <li> child elements under the <ul> element, and use # The ##index() method obtains the position of the selected <li> element in its parent element.

As a result, the number obtained is 1, which means that the position of the selected

<li> element is the second among its parent elements.

In summary, by combining the three methods

parent(), children() and index(), we can easily Get the position of an element within its parent element. This is a very common requirement for jQuery in DOM operations, and it is also one of the most practical methods in jQuery.

The above is the detailed content of How to get the position of an element in its parent element with jquery. For more information, please follow other related articles on the PHP Chinese website!