What does colon mean in jquery?

jQuery is a JavaScript library that is commonly used to operate HTML documents, handle events, animation effects, Ajax interactions, etc. In jQuery, the colon is a very important symbol with many different uses. Let’s introduce some common meanings of colons in jquery.

1. Selector

In jQuery, selectors can select specific elements in the DOM tree. The colon is a symbol often used in selectors. For example, we can use the ":even" selector to select all even-numbered elements in an HTML document:

$("tr:even")

This code means to select all even-numbered elements in the HTML document. Similarly, we can also use ":odd" to select elements at odd positions.

In addition to "even" and "odd", jQuery also provides many other selectors, such as ":first", ":last", ":nth-child", etc., all of which are It can help us select the elements we need more conveniently and quickly.

2. Pseudo-class

In CSS, pseudo-class represents the style of an element in a specific state. In jQuery, there are also some specific pseudo-classes that can help us select or operate elements in specific states. For example, ":hover" represents the state when the mouse hovers over the element. We can use it to bind the mouse hover event:

$("button:hover").css("background-color", "red");

This code represents when the mouse hovers over the element, set its background color to red.

In addition to ":hover", other pseudo-classes supported by jQuery include ":focus", ":active", ":checked", etc. These pseudo-classes can help us better handle the display effects of elements in different states.

3. Pseudo elements

In HTML documents, there are some elements that do not exist in the DOM tree, such as :before, :after and other pseudo elements. In jQuery, pseudo-elements are also supported to operate elements.

For example, we can use ":before" to add content or style before an element:

$("p:before").css("content", "hello");

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This code means adding "hello" text in front of all

elements. Likewise, ":after" and ":before" are used very similarly.

Summary

In jQuery, the colon is a very important symbol with many different uses. In addition to the selectors, pseudo-classes and pseudo-elements introduced above, there are many other specific colon usages, such as ":input", ":password" and so on. Proficient use of these colons can help us operate elements in HTML documents more conveniently and quickly.

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