What does eq mean in jquery

jQuery is a popular JavaScript library that simplifies many tasks common in JavaScript programming, such as DOM traversal, event handling, animation, and more. One of the commonly used methods is the eq() method, which is a selector that can select specified elements from a set of matching elements based on the index value.

In jQuery, many methods can accept an index value as a parameter to select a specific element. The same is true for the eq() method. It will filter the elements in the matching element collection according to the index value and only select elements that meet the conditions.

eq()The method accepts an integer parameter, which represents the index position in the set of matching elements. This index starts from 0, that is, the index of the first element is 0, and the index of the second element is 0. The index of an element is 1, and so on. For example, $("li").eq(2) will select the third li element in the set of matched elements.

Here are some sample codes to better understand the usage of eq() method:

//选取第一个p元素
$("p").eq(0).css("background-color", "yellow");

//选取最后一个span元素并隐藏它
$("span").eq(-1).hide();

//遍历每一个li元素，并选取其中索引为偶数的元素
$("li").each(function(index){
  if (index % 2 === 0) {
    $(this).addClass("even");
  }
});

In the above code, the first example selects the matching element The first p element in the collection and sets its background color to yellow; the second example selects the last span element and hides it; the third example traverses each li element and selects the even index elements and add a class to them.

In actual development, the eq() method is very useful because it can help developers easily select specified elements in a collection of matching elements without writing complex selectors. At the same time, there are many other selectors in jQuery, which can also be very convenient to help us select specific elements, greatly simplifying JavaScript programming.

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