jQuery study notes: $_jquery in jQuery

In jQuery, the most commonly used one is the dollar sign $, which provides a variety of rich functions. Including selecting one or a type of element in the page, prefixing it as a functional function, improving windows.onload, creating DOM nodes, etc. This article introduces the usage of jQuery. As a basis

1. Selector

In CSS, the function of a selector is to select a certain type of element (category selector) or an element (id selector) on the page. As a selector, "$" in jQuery also selects a certain type or element, but jQuery provides a more comprehensive selection method. And it solves browser compatibility issues for users.

For example, in the element under css

, css:

h2 a{
/* Add css attributes */}
In jQuery, use the following code to select the a element under h2 as an object array for use by javascript.

$("H2 a")
Example:

Copy code The code is as follows:

         

$(selector) or

jQuery(selector)

Among them, selector complies with css standards, even css3 standards

For example:

$("#showDiv")

The id selector is equivalent to document.getElementById("shouDiv") in JavaScript. You can see that jQuery's color changing method is much simpler.

$(".newClass")

Category selector, selects nodes whose CSS category is "newClass" element. To achieve the same selection in JavaScript, you need to use a for loop to traverse the entire DOM

$("p:odd")
Selects all p elements in odd-numbered rows. Almost all tags can be used to select odd and even selections using ":odd" and ":even".

$("td:nth-child(1)")
Select the first cell of all table rows, which is the first column. This is very useful when modifying a column of a table without having to traverse the table row by row.

$("li>a")
Child selector, returns the element marked under

, excluding the grandchild element mark

$("a[herf$=pdf]")
Attribute selector selects all hyperlinks that end with pdf. With the attribute selector, you can easily select elements with various characteristics on the page

Summary:

$ is another name for jQuery

And jQuery is a function provided by the jQuery library. (It seems that it is not just a function, because there is also the use of $.ajax(options), which is equivalent to jQuery.ajax(options))

The function of this function is to search and select elements in the html document based on the parameters in (). One of the functions of the function is to replace GetElementByID, but () can not only be ID, but also various selectors