Let's talk about how to implement the loading progress bar function in PHP

In most websites, you will encounter the need to partially refresh the page through Ajax technology. In many cases, a loading progress bar is needed to improve the user experience. This article will talk about how to implement a loading progress bar in PHP.

1. What is Ajax technology?

Ajax (Asynchronous JavaScript and XML) technology is a browser-based client-side script technology that updates partial pages by asynchronously transmitting data with the server. Its biggest feature is asynchronous transmission, which updates data without refreshing the entire page. This is also the main reason why it can improve user experience.

2. How to implement the loading progress bar

The implementation of the loading progress bar can be achieved mainly in the following two ways.

1. CSS3 implementation

The method of CSS3 implementation is relatively simple, and you only need to use CSS to implement it. The style code is as follows:

/*设置进度条的宽度 */
.progress-wrap {
  width: 100%;
  height: 5px;
  position: fixed;
  top: 0;
  left: 0;
  overflow: hidden;
  z-index: 99999;
}
/*设置进度条的颜色 */
.progress-bar {
  width: 0;
  height: 5px;
  background-color: #5ea9dd;
  animation: progress-bar 2.5s linear;
}
/*设置进度动画 */
@keyframes progress-bar {
  from { width: 0; }
  to { width: 100%; }
}

2. JavaScript implementation

The JavaScript implementation method is slightly more complicated and needs to be implemented using the XMLHttpRequest object and its events.

First, we need to add the HTML code of the progress bar to the page:

<!--加载进度条-->
<div id="loading" class="loading">
  <div class="loading-container">
    <div class="loading-progress">
      <div class="loading-bar"></div>
    </div>
  </div>
</div>

Then, we need to style the progress bar in CSS:

/*加载进度条*/
.loading {
  position: fixed;
  z-index: 9999;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  background-color: rgba(0,0,0,.5);
}
.loading .loading-container {
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
}
.loading .loading-progress {
  margin: 0 auto;
  width: 200px;
  height: 5px;
  background-color: rgba(255,255,255,.3);
  border-radius: 5px;
}
.loading .loading-progress .loading-bar {
  height: 5px;
  background-color: #fff;
  border-radius: 5px;
  animation: loading 2.5s linear;
}
/*设置进度动画*/
@keyframes loading {
  from {
    width: 0;
  }
  to {
    width: 100%;
  }
}

Finally , we need to implement the relevant logic of Ajax asynchronous requests in JavaScript:

//创建 XMLHttpRequest 对象
var xhr = new XMLHttpRequest();
//设置监听事件
xhr.onreadystatechange = function () {
  //请求完成后
  if (xhr.readyState == 4) {
    //隐藏进度条
    $('#loading').fadeOut(300);
    //请求成功
    if (xhr.status == 200) {
      //处理响应数据...
    }
    //请求失败
    else {
      //处理错误...
    }
  }
}
//发送请求
xhr.open('GET', '/path/to/server', true);
xhr.send(null);
//显示进度条
$('#loading').fadeIn(300);

3. Summary

The method for PHP to implement the loading progress bar is relatively simple. We can use CSS3 or JavaScript. to fulfill. However, using JavaScript allows you to more freely control the display timing of the progress bar and the processing of data. In the actual development process, we can flexibly choose an implementation method that suits us based on actual needs.

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