What is the eq method in jquery?

jQuery ($ for short) is a JavaScript library that encapsulates DOM operations commonly used in JavaScript, making operations more convenient and efficient. In jQuery, we often use the eq method. This article will explain the eq method in detail.

The eq method refers to selecting a specific element from the matching element set, and the index starts from 0. For example, if you need to select the 4th element, you can use eq(3).

The syntax format of the eq method is as follows:

$(selector).eq(index)

Among them, selector represents the selector of the element you want to operate, which can be the element's tag name, class name, ID, etc.; index represents your The index of the element to select, counting from 0.

If there is no element with the corresponding index in the element set matched by the selector, the eq method will return an empty set.

Here are a few examples of using the eq method:

// 选中class为box的第一个元素
$(".box").eq(0)

// 选中ul中的第二个li元素
$("ul li").eq(1)

// 选中ID为myDiv的第三个直接子元素
$("#myDiv > *").eq(2)

It should be noted that when a negative number is passed to the eq method, it will start counting from the end of the set. For example, eq(-1) means selecting the last element in the set, eq(-2) means selecting the second to last element, and so on.

In addition to the eq method, there are some similar methods, such as first, last, slice, etc., which can also be used to select one or more elements in the set.

• first method: select the first element in the collection
• last method: select the last element in the collection
• slice method: select a segment in the collection Element

The following are several examples of using the first, last and slice methods:

// 选中class为box的第一个元素
$(".box").first()

// 选中ul中的最后一个li元素
$("ul li").last()

// 选中ID为myDiv的第二个到第四个直接子元素
$("#myDiv > *").slice(1,4)

In actual development, the eq method is widely used. For example, the eq method is very useful when you need to select one element from multiple elements for operation. In addition, in loop operations, the eq method can also be used to select one or more elements in the set.

In short, eq is a very practical method in jQuery. Mastering its use can allow us to operate DOM more efficiently.

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