Detailed explanation of jQuery lazyload lazy loading

Lazy Load is a jQuery plug-in written in JavaScript. It can delay loading of images in long pages. Images outside the browser's visible area will not be loaded until the user scrolls the page to where they are. This is exactly the opposite of how image preloading is handled.

Lazy loading of images on long pages that contain many large images can speed up page loading. The browser will enter the ready state after loading the visible images. In some cases, it can also help reduce the load on the server.

Demo page:

Basic options

Fade-in effect

For browsers that do not support JavaScript Downgrade processing

Horizontal scrolling

Horizontal scrolling within the container

Vertical scrolling within the container

There are many N pictures in the page

After five years Load images after a delay of seconds

Use AJAX to load images

How to use

Lazy Load relies on jQuery. Please add the following code to the end of the HTML, that is < ;/body>Before:

<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="jquery.lazyload.js"></script>

You have to change the tag of the image. The address of the image must be placed on the data-original attribute. Give lazy loading images a specific class (for example: lazy). This way you can easily do image plugin bundling. The code is as follows:

<img class="lazy" alt="" width="640" height="480" data-original="img/example.jpg" />
$(function() {
 $("img.lazy").lazyload();
});

This will cause all images with class lazy to be loaded lazily.

Demo: Basic Options

TIPS: The width and height of the image must be set here, otherwise the plug-in may not work properly.

Set the threshold

By default, the image will be loaded when it appears on the screen. If you want to load the image in advance, you can set the threshold option. Set the threshold to 200 so that the image is 200 pixels away from the screen. Early loading.

$("img.lazy").lazyload({
 threshold : 200
});

Set events to trigger loading

You can use jQuery events such as click and mouseover. You can also use custom events, such as sporty and foobar. The default is to wait until the user scrolls down and the image appears in the viewport. Load images only when the user clicks on them:

$("img.lazy").lazyload({
 event : "click"
});

Demo: Load images after a five-second delay

Use special effects

By default, the plugin waits for the image to fully load and calls show(). You can use any effect you want. The code below uses fadeIn (fade in effect).

Demo: Fade in effect

$("img.lazy").lazyload({
 effect : "fadeIn"
});

For situations where JavaScript is not enabled

JavaScript for almost all browsers are all enabled. However, you may still want to display real images on clients that do not support JavaScript. To degrade gracefully when the browser does not support JavaScript, you can write the real image fragment in the 2b0b25ff593c5b6c03403dd6234ffb2c tag.

<img class="lazy" data-original="img/example.jpg" width="640" heigh="480">
<noscript><img src="img/example.jpg" width="640" heigh="480"></noscript>

##You can hide placeholders through CSS.

.lazy {
 display: none;
}

In browsers that support JavaScript, you must display the placeholder when the DOM is ready, which can be done at the same time as the plugin is initialized.

$("img.lazy").show().lazyload ();

Images in containers

You can use plug-ins on images in scrollable containers, such as DIV elements with scroll bars. All you have to do is define the container as jQuery The object is passed as a parameter to the initialization method.

Demo: horizontal scrolling in the container, vertical scrolling in the container

When the image is not continuous

When scrolling the page, Lazy Load will loop through the loaded images. During the loop, it is checked whether the image is within the visible area. By default, the loop stops when the first image that is not in the visible area is found. The image is considered to be distributed in a streaming manner, and the image is in the page The order is the same as that in HTML code. But in some layouts, this assumption is not true. However, you can control the loading behavior through the failurelimit option.

$("img.lazy").lazyload({
 failure_limit : 10
});

Set failurelimit to 10, so that the plug-in will stop searching only when it finds 10 images that are not in the visible area. If you have a cumbersome layout, please set this parameter higher.

Loading Hide There may be many hidden pictures buried on your page. For example, if the plug-in is used to filter the list, you can constantly modify the display status of each item in the list. In order to improve performance, Lazy Load defaults Hidden images are ignored. If you want to load hidden images, please set skip_invisible to false

$("img.lazy").lazyload({
 skip_invisible : false
});

Download plugin

Latest version source code and compressed code. The plug-in is already available on OSX’s Safari 5.1, Safari 6, Chrome 20, Firefox 12 browsers, Windows’ Chrome 20, IE 8 and IE 9 browsers, and iOS5 (iPhone and Tested on Safari 5.1 browser of iPad).

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