How to use jquery in projects

With the continuous development of web technology, JavaScript has become a necessary skill in web development. As one of the most popular JavaScript libraries, jQuery has also attracted much attention in many projects. This article will introduce how to use jQuery in your project.

1. Introduce the jQuery library

To use jQuery, you must first introduce the jQuery library into the page. You can download the jQuery library file yourself and import it, or you can use a CDN (Content Delivery Network) to import it.

The code to use CDN to introduce the jQuery core library is as follows:

<script src="https://cdn.jsdelivr.net/jquery/3.6.0/jquery.min.js"></script>

2. Use jQuery selector to obtain elements

jQuery selector can easily obtain the elements of the page. Common selectors are:

1. Element selector

   $('p')  // 获取页面中所有 <p> 元素

2. id selector

   $('#myId')  // 获取 ID 为 myId 的元素

3. class selector

   $('.myClass')  // 获取 class 为 myClass 的元素

4. Attribute selector

   $('[href]')  // 获取所有包含 href 属性的元素

5. Descendant selector

   $('ul li')  // 获取所有 <ul> 下的 <li> 元素

3. Use jQuery to operate elements

After obtaining the element, you can use the methods provided by jQuery to operate.

1. Modify element attributes

   $('img').attr('src', 'newSrc.jpg')  // 修改所有 <img> 元素的 src 属性

2. Modify element content

   $('div').text('newText')  // 将所有 <div> 元素的文本内容改为 newText

3. Show/hide elements

   $('p').show()  // 显示所有 <p> 元素
   $('p').hide()  // 隐藏所有 <p> 元素

4. Add/Delete Element

   $('ul').append('<li>New item</li>')  // 在所有 <ul> 元素的末尾添加一个 <li> 元素
   $('ul li:last-child').remove()  // 删除所有 <ul> 元素中最后一个 <li> 元素

5. Bind Event

   $('button').click(function () {
     alert('Button clicked!')
   })  // 给所有 <button> 元素绑定 click 事件

4. Use AJAX to send a request

jQuery provides a convenient AJAX method that can send requests to the server without refreshing the page.

$.ajax({
  url: '/getdata',
  type: 'GET',
  dataType: 'json',
  success: function (data) {
    console.log(data)
  },
  error: function (xhr, status, error) {
    console.log(error)
  }
})

The above code will send a GET request to the server to obtain the returned JSON data. If the request is successful, the data will be output to the console. If the request fails, an error message will be output.

5. Summary

jQuery can greatly simplify the development process in the project and improve efficiency. What is introduced in this article is just the tip of the iceberg of jQuery. There are many methods and techniques that you need to learn and master in depth.

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