Lazy Loading

An optimization strategy for online content, encompassing websites and web applications. This technique deviates from the conventional approach of loading an entire web page and promptly displaying it to users. Instead, lazy loading focuses on loading only the pertinent section, deferring the remaining content until the user necessitates its display.

One manifestation of the technique is the concept of infinite scrollingScrollingThe act of moving content vertically or horizontally on a digital screen.
More About Scrolling. In this method, webpage content is progressively loaded as the user scrolls downward. This technique enjoys popularity across diverse websites to optimize content delivery.

Benefits

• Time and Memory Efficiency. On-demand loading reduces time consumption and memory usage, optimizing content delivery. The loading timeLoad TimeThe amount of time it takes for a webpage or app to load and become interactive for the user fully.
  More About Load Time is minimized by loading only the essential portion of the webpage initially. Subsequent sections are loaded with a delay, conserving storage space. This rapid delivery of requested content significantly enhances the user experience.
• Elimination of Unnecessary Code Execution. Lazy loading prevents the execution of unnecessary code, enhancing overall performancePerformanceRefers to how fast a website or web application loads and responds to user interactions.
  More About Performance.
• Resource Optimization. This approach effectively utilizes time and space resources, making it a cost-effective solution from a business perspective, especially for website owners.

Drawbacks

• Increased Code Complexity. Implementing lazy loading requires adding extra lines of code to the existing ones, potentially complicating the codebase.
• Potential SEOSEOSearch Engine Optimization involves optimizing various website elements to make it more attractive to search engines like Google, Bing, and Yahoo.
  More About SEO Impact. Lazy loading might adversely affect a website’s search engine ranking due to improper indexingIndexingOrganizing and categorizing vast amounts of information, such as web pages, documents, or even books, to allow quick and accurate retrieval.
  More About Indexing of unloaded content. This can lead to reduced visibility in search results.

Implementing Lazy Loading for Images

One approach to implementing the technique involves utilizing the HTMLHTMLThe fundamental language used to create and structure content on web pages.
More About HTML attributeAttributeDefines the size, color, alignment, and other visual properties of an element.
More About Attribute “loading” within an image tag. By including loading=”lazy” as demonstrated in the following example, the browserBrowserA software application that enables you to view and interact with websites.
More About Browser is instructed to postpone image loading until the user scrolls in proximity to it:

<img src="example.com/image" alt="example image" width="100" height="100" loading="lazy">

Web developers also have the option to leverage programming frameworksFrameworksA pre-established structure or set of guidelines that provides developers with a foundation to build upon.
More About Frameworks for more advanced lazy loading functionalities. Angular is a commonly employed framework for this purpose. Additionally, the JavaScriptJavascriptA high-level, dynamic, and interpreted programming language primarily used to create interactive and responsive user interfaces on web pages.
More About Javascript library ReactReactA JavaScript library developed by Facebook for building user interfaces, particularly for single-page applications, by creating reusable UI components.
More About React provides support for implementing the techniques.

Other Page Resources Suitable for the Technique

• JavaScript, a resource that often causes rendering delays, can be optimized through lazy loading. Dividing JavaScript code into smaller modules and loading them as needed minimizes page load times, especially for pages reliant on JavaScript execution.
• CSSCSSCascading Style Sheets is a coding language that determines the appearance and layout of a website.
  More About CSS, another render-blocking resource, can benefit from the technique. Breaking a CSS file into multiple parts that load selectively reduces the duration a browser is hindered from rendering content. Non-blocking CSS files should possess separate links, accompanied by a media property indicating when they should be loaded.
• iframes serve to embed external content within a webpage. The same HTML loading attribute mentioned earlier for images can be applied to iframe tags. This approach delays iframes loading until they approach the visible portion, optimizing resource utilization.