Ajax asynchronous loading image example analysis
This article mainly introduces the method of asynchronous loading of ajax images. It analyzes the principles and related implementation techniques of asynchronous loading of ajax images in detail in the form of examples. Friends in need can refer to the following
Examples of this article Ajax method for asynchronously loading images. I share it with you for your reference. The details are as follows:
Pictures are generally relatively large, so they are loaded gradually after the basic web page is loaded. The whole loading process is very unsightly, or it gradually changes from blurry to blurry. Clear, or expanded from top to bottom (of course you can also think that these are good special effects). If the dynamic replacement of the image is achieved by regularly changing the src attribute of the img, the resulting flicker will be even more unacceptable. This is not something that can be pleasant with the alt attribute.
Contact the popular AJAX technology, which is known as "no" refresh. It uses the XMLHttpRequest object to initiate an asynchronous request. After the image is loaded, it is dynamically inserted into the "foreground" HTML page. It should be able to meet the needs, but the object returned by the XMLHttpRequest object has only two attributes, responseXML and responseText. The former is an XML object, and the latter is the returned plain text content. It seems that there is no binary data required for the picture... Taking a step back, even if it can be used responseText retrieves the binary data of the image, how can we insert it into the front page? Replace the src attribute of img with the requested url?
Just do it and write an image slideshow code to verify your idea:
<html>
<head>
<title>Image Slide</title>
<script>
function makeAsyncRequest(url, callback)
{
var httpRequest;
if (window.XMLHttpRequest) { // Mozilla, Safari, ...
httpRequest = new XMLHttpRequest();
if (httpRequest.overrideMimeType) {
httpRequest.overrideMimeType('text/xml');
}
} else if (window.ActiveXObject) { // IE
try {
httpRequest = new ActiveXObject("Msxml2.XMLHTTP");
} catch (e) {
try {
httpRequest = new ActiveXObject("Microsoft.XMLHTTP");
} catch (e) {
}
}
}
httpRequest.onreadystatechange = function () {
if (httpRequest.readyState == 4
&& httpRequest.status == 200)
callback(url);
};
httpRequest.open('GET', url, true);
httpRequest.send('');
}
var i = 0;
var max_i = 10;
function displayImage()
{
var url = "./" + i + ".jpg";
makeAsyncRequest(url, function (url) {
var p = document.getElementById("image");
var img = p.getElementsByTagName("img");
if (img.length == 0) {
img = document.createElement("img");
while (p.childNodes.length > 0)
p.removeChild(p.childNodes[0]);
p.appendChild(img);
} else
img = img.item(0);
img.src = url;
if (i == max_i)
i = 0;
else
i ++;
window.setTimeout("displayImage();", 1000);
});
}
</script>
</head>
<body onload="displayImage();">
<p id="image">
</p>
</body>
</html>The above code displays pictures 0.jpg - 10.jpg in a loop at a time interval of 1000 milliseconds. The effect is more obvious and flickering is indeed eliminated. So how does it work? The display of each image is divided into two steps:
Use the XMLHttpRequest object to obtain the image from the server, and cache the image to the local browser buffer.
Get the image from the local browser buffer for display.
Because the time from taking the picture to displaying it in the second step is very short, the user basically cannot detect any flicker. It can be seen that the above technology is based on the assumption that the requested image is cacheable. If the image is not cacheable, will the above code not work properly?
Let the code speak for itself and make some changes to the above code:
function displayImage()
{
var url = "./" + i + ".jpg";
var url = "./image.php?filename=" + i + ".jpg";
makeAsyncRequest(url, function (url) {
var p = document.getElementById("image");
var img = p.getElementsByTagName("img");Write another php script to transmit the requested image:
<?php
header("Content-Type: image/jpeg");
header("Cache-Control: no-cache");
echo file_get_contents($_GET["filename"]);
?>As expected , it flickered again...
It seems that we need to think of another way. Working behind closed doors will not work. Please ask Mr. Google for help! The hard work paid off, and I finally found it. I was overjoyed. The result still surprised me. IMG actually has an onload event callback interface. I can only be glad that my glasses are made of resin. "I am not afraid if my glasses fall off." Well, don't be afraid, don't be afraid, don't be afraid..."
What are you waiting for? Of course the code will serve you:
<html>
<head>
<title>Image Slide</title>
<script>
var i = 0;
var max_i = 10;
function displayImage()
{
var img = document.createElement("img");
img.onload = function () {
var p = document.getElementById("image");
while (p.childNodes.length > 0)
p.removeChild(p.childNodes[0]);
p.appendChild(img);
if (i == max_i)
i = 0;
else
i ++;
window.setTimeout("displayImage();", 1000);
}
img.src = "./" + i + ".jpg";
}
</script>
</head>
<body onload="displayImage();">
<p id="image">
</p>
</body>
</html>"She is an ungly girl!"Nothing to say, non-cacheable image Situation:
i ++;
window.setTimeout("displayImage();", 1000);
}
img.src = "./" + i + ".jpg";
img.src = "./image.php?filename=" + i + ".jpg";
}
</script>
</head>The above is what I compiled for everyone. I hope it will be helpful to everyone in the future.
Related articles:
AJAX request queue implementation
Summary of several methods of using ajax to submit forms asynchronously
How to solve the problem of arrays in AJAX requests
The above is the detailed content of Ajax asynchronous loading image example analysis. For more information, please follow other related articles on the PHP Chinese website!
Hot AI Tools
Undresser.AI Undress
AI-powered app for creating realistic nude photos
AI Clothes Remover
Online AI tool for removing clothes from photos.
Undress AI Tool
Undress images for free
Clothoff.io
AI clothes remover
AI Hentai Generator
Generate AI Hentai for free.
Hot Article
Hot Tools
Notepad++7.3.1
Easy-to-use and free code editor
SublimeText3 Chinese version
Chinese version, very easy to use
Zend Studio 13.0.1
Powerful PHP integrated development environment
Dreamweaver CS6
Visual web development tools
SublimeText3 Mac version
God-level code editing software (SublimeText3)
Hot Topics
1377
52
How to solve the problem of automatically saving pictures when publishing on Xiaohongshu? Where is the automatically saved image when posting?
Mar 22, 2024 am 08:06 AM
With the continuous development of social media, Xiaohongshu has become a platform for more and more young people to share their lives and discover beautiful things. Many users are troubled by auto-save issues when posting images. So, how to solve this problem? 1. How to solve the problem of automatically saving pictures when publishing on Xiaohongshu? 1. Clear the cache First, we can try to clear the cache data of Xiaohongshu. The steps are as follows: (1) Open Xiaohongshu and click the "My" button in the lower right corner; (2) On the personal center page, find "Settings" and click it; (3) Scroll down and find the "Clear Cache" option. Click OK. After clearing the cache, re-enter Xiaohongshu and try to post pictures to see if the automatic saving problem is solved. 2. Update the Xiaohongshu version to ensure that your Xiaohongshu
How to post pictures in TikTok comments? Where is the entrance to the pictures in the comment area?
Mar 21, 2024 pm 09:12 PM
With the popularity of Douyin short videos, user interactions in the comment area have become more colorful. Some users wish to share images in comments to better express their opinions or emotions. So, how to post pictures in TikTok comments? This article will answer this question in detail and provide you with some related tips and precautions. 1. How to post pictures in Douyin comments? 1. Open Douyin: First, you need to open Douyin APP and log in to your account. 2. Find the comment area: When browsing or posting a short video, find the place where you want to comment and click the "Comment" button. 3. Enter your comment content: Enter your comment content in the comment area. 4. Choose to send a picture: In the interface for entering comment content, you will see a "picture" button or a "+" button, click
6 Ways to Make Pictures Sharper on iPhone
Mar 04, 2024 pm 06:25 PM
Apple's recent iPhones capture memories with crisp detail, saturation and brightness. But sometimes, you may encounter some issues that may cause the image to look less clear. While autofocus on iPhone cameras has come a long way, allowing you to take photos quickly, the camera can mistakenly focus on the wrong subject in certain situations, making the photo blurry in unwanted areas. If your photos on your iPhone look out of focus or lack sharpness overall, the following post should help you make them sharper. How to Make Pictures Clearer on iPhone [6 Methods] You can try using the native Photos app to clean up your photos. If you want more features and options
How to make ppt pictures appear one by one
Mar 25, 2024 pm 04:00 PM
In PowerPoint, it is a common technique to display pictures one by one, which can be achieved by setting animation effects. This guide details the steps to implement this technique, including basic setup, image insertion, adding animation, and adjusting animation order and timing. Additionally, advanced settings and adjustments are provided, such as using triggers, adjusting animation speed and order, and previewing animation effects. By following these steps and tips, users can easily set up pictures to appear one after another in PowerPoint, thereby enhancing the visual impact of the presentation and grabbing the attention of the audience.
How to convert pdf documents into jpg images with Foxit PDF Reader - How to convert pdf documents into jpg images with Foxit PDF Reader
Mar 04, 2024 pm 05:49 PM
Are you also using Foxit PDF Reader software? So do you know how Foxit PDF Reader converts pdf documents into jpg images? The following article brings you how Foxit PDF Reader converts pdf documents into jpg images. For those who are interested in the method of converting jpg images, please come and take a look below. First start Foxit PDF Reader, then find "Features" on the top toolbar, and then select the "PDF to Others" function. Next, open a web page called "Foxit PDF Online Conversion". Click the "Login" button on the upper right side of the page to log in, and then turn on the "PDF to Image" function. Then click the upload button and add the pdf file you want to convert into an image. After adding it, click "Start Conversion"
What should I do if the images on the webpage cannot be loaded? 6 solutions
Mar 15, 2024 am 10:30 AM
Some netizens found that when they opened the browser web page, the pictures on the web page could not be loaded for a long time. What happened? I checked that the network is normal, so where is the problem? The editor below will introduce to you six solutions to the problem that web page images cannot be loaded. Web page images cannot be loaded: 1. Internet speed problem The web page cannot display images. It may be because the computer's Internet speed is relatively slow and there are more softwares opened on the computer. And the images we access are relatively large, which may be due to loading timeout. As a result, the picture cannot be displayed. You can turn off the software that consumes more network speed. You can go to the task manager to check. 2. Too many visitors. If the webpage cannot display pictures, it may be because the webpages we visited were visited at the same time.
How to arrange two pictures side by side in wps document
Mar 20, 2024 pm 04:00 PM
When using WPS office software, we found that not only one form is used, tables and pictures can be added to the text, pictures can also be added to the table, etc. These are all used together to make the content of the entire document look richer. , if you need to insert two pictures into the document and they need to be arranged side by side. Our next course can solve this problem: how to place two pictures side by side in a wps document. 1. First, you need to open the WPS software and find the picture you want to adjust. Left-click the picture and a menu bar will pop up, select "Page Layout". 2. Select "Tight wrapping" in text wrapping. 3. After all the pictures you need are confirmed to be set to "Tight text wrapping", you can drag the pictures to the appropriate position and click on the first picture.
How to solve the 403 error encountered by jQuery AJAX request
Feb 20, 2024 am 10:07 AM
Title: Methods and code examples to resolve 403 errors in jQuery AJAX requests. The 403 error refers to a request that the server prohibits access to a resource. This error usually occurs because the request lacks permissions or is rejected by the server. When making jQueryAJAX requests, you sometimes encounter this situation. This article will introduce how to solve this problem and provide code examples. Solution: Check permissions: First ensure that the requested URL address is correct and verify that you have sufficient permissions to access the resource.
