You need to import the jquery.js file before using jquery. Two import methods: 1. Download the jquery file locally from the jquery official website, and use the script tag to import the local jquery file. The syntax is ""; 2. Use script The tag imports the online jquery file with the syntax "".
The operating environment of this tutorial: windows7 system, jquery3.6 version, Dell G3 computer.
1. Introduction to jQuery
- ##jQuery is a js library that stores function() written in js code .
- The original intention of jQuery is to simplify JS code.
- Can handle HTML/JSP/XML, CSS, DOM, events, and also provide asynchronous AJAX functionality.
- For example:
document.getElementByid()
Encapsulates a method in jQuery:
function $("#id"){//函数名是$ return document.getElementById(id); }
2. Use:
jQuery is actually a js file. When we use it, we first need to introduce the file into the HTML document. There are two ways to import jquery, one is local import and the other is import from hyperlink.Introduction method one: local introduction
We can search jquery on Baidu and find the official website of jquery: https://jquery.com/You can download the latest version of jquery from here. Click the download icon and you will jump to the download details page:<script ></script> <script> //在此书写你的jquery代码 </script>
Introduction method two: introduce online jquery
We can import the online jquery code by writing a URL in the src attribute of the script. Someone may want to ask, Wouldn't this cause a delay in downloading jquery when the web page is loading? Will it take a long time to download, causing your jquery code to never be loaded, affecting the user experience? In fact, there are many websites that use jquery now. The browser will pre-download jquery when loading the website that used jquery before, so we don’t need to download it again, even if our jquery version is It is a new version that has not been loaded by the browser, and the jquery code will be downloaded very quickly. However, if you are still worried about affecting the loading speed, importing the jquery file locally is indeed the best way. For example, the online JQ file of jquery official website: https://code.jquery.com/jquery-3.6.0.min.js<script src="https://code.jquery.com/jquery-3.6.0.min.js"></script> <script> //在此书写你的jquery代码 </script>
Usage:
Create jQuery objects to call functions in the library[Recommended learning:jQuery video tutorial 、webfront-end video】
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