What is the out-of-bounds return value of jquery eq()

When using jQuery's eq() method, sometimes we encounter out-of-bounds situations. So here comes the question: What is the out-of-bounds return value of jQuery's eq()?

First, let’s understand how to use eq(). eq() is a jQuery selector method used to select elements at specified index positions. For example, if we have a list of three elements, we can use the following code to select the second element:

$("li").eq(1);

In this example, we use eq(1) to select the second li element . Note that the indexing of the eq() method starts at 0, so the first element has index 0, the second element has index 1, and so on.

So, what if the index we pass to the eq() method is greater than or equal to the length of the list? For example, if the index we pass to the eq() method is 3, but our list only has three elements:

$("li").eq(3);

At this time, the eq() method will return a jQuery object with a length of 0. So if we try to call any jQuery methods on this object, these methods will have no effect. For example, if we try to call the addClass() method after the above code:

$("li").eq(3).addClass("active");

This statement will have no effect because $("li").eq(3) returns an empty jQuery object.

In addition, we can also obtain the element at the specified index position by using the get() method. The get() method returns a DOM element, not a jQuery object. If we try to get an element at an index that does not exist, the get() method will return undefined. For example:

$("li").get(3); // 返回undefined

To sum up, jQuery's eq() method will return a jQuery object with a length of 0 when the index is out of bounds. We should pay special attention to this situation to avoid unnecessary errors.

The above is the detailed content of What is the out-of-bounds return value of jquery eq(). For more information, please follow other related articles on the PHP Chinese website!