What are the methods of lazy loading?

The methods of lazy loading include lazy loading of pictures, lazy loading of videos, lazy loading of script files, lazy loading of data, etc. Detailed introduction: 1. Image lazy loading is a common lazy loading implementation method. When the page is loaded, only the images in the visible area are loaded, and the images in other areas are presented in the form of placeholders. When the user scrolls the page to The real image is loaded when the image position is specified. Image lazy loading can be achieved by using the existing JavaScript library or custom code; 2. Video lazy loading is implemented in a similar way to image lazy loading, such as when the page is loading, etc.

The operating system for this tutorial: Windows 10 system, DELL G3 computer.

Lazy loading is a programming pattern usually used to optimize resource loading and page performance. The goal of this strategy is to load specific resources or data only when needed, thereby avoiding loading all resources at the beginning to reduce page load time and improve page performance. Lazy loading is usually used to load resources such as images, videos, script files, and data.

There are several methods of lazy loading:

1. Lazy loading of pictures

Lazy loading of pictures is a common lazy loading implementation method. When the page loads, only images in the visible area are loaded, and images in other areas are presented as placeholders. When the user scrolls the page to the image position, the real image is loaded. Lazy loading of images can be implemented using existing JavaScript libraries (such as imagesLoaded) or custom code.

The basic steps to implement lazy loading of images are as follows:

(1) Insert a placeholder image into the page. The size and position of the placeholder image are the same as the actual image.

(2) Use JavaScript code to listen to scroll events and determine the position of the current visual area.

(3) When the user scrolls to the location of the placeholder image, obtain the URL of the actual image through an AJAX request, and insert the image into the page.

(4) Use JavaScript code to monitor the loading event of the image. When the image is loaded, delete the placeholder image.

2. Video lazy loading

The implementation of video lazy loading is similar to that of image lazy loading. When the page is loaded, only the video player in the visible area is loaded, and other areas are loaded. Presented in placeholder form. When the user scrolls the page to the video position, the video file starts loading. Implementing lazy loading of videos can be achieved by using existing JavaScript libraries or custom code.

The basic steps to implement lazy loading of videos are as follows:

(1) Insert a placeholder video player into the page. The size and position of the placeholder video player are the same as the actual video player. same.

(2) Use JavaScript code to listen to scroll events and determine the position of the current visual area.

(3) When the user scrolls to the location of the placeholder video player, obtain the URL of the actual video file through an AJAX request, and insert the video file into the page.

(4) Use JavaScript code to monitor the loading event of the video file. When the video file is loaded, delete the placeholder video player.

3. Lazy loading of script files

Lazy loading of script files can delay loading of script files to the bottom of the page to avoid blocking the rendering of the page. By using event listeners, script files can be loaded only when needed. Implementing lazy loading of script files can be achieved by using existing JavaScript libraries or custom code.

The basic steps to implement lazy loading of script files are as follows:

(1) Insert the placeholder tag of the script file at the bottom of the page.

(2) Use JavaScript code to listen to specific events (such as click events). When the event occurs, obtain the URL of the script file through an AJAX request, and insert the script file into the page.

(3) Use JavaScript code to monitor the loading completion event of the script file, and execute the corresponding function when the script file is loaded.

4. Lazy loading of data

Lazy loading of data can only load part of the data when the page is initialized, and only load other data when the user needs it. This method can reduce the amount of data for page initialization and improve page performance. Implementing lazy loading of data can be achieved by using existing JavaScript libraries or custom code.

The basic steps to implement lazy loading of data are as follows:

(1) Insert a placeholder container for data into the page.

(2) Use JavaScript code to listen to specific events (such as scroll events or click events). When the event occurs, obtain the URL of the data through an AJAX request and insert the data into the page.

(3) Use JavaScript code to monitor the data loading completion event, and execute the corresponding function when the data loading is completed.

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