Description: Delay loading is a web performance optimization technique that postpones the loading of non-essential resources until they are actually needed. This means that instead of loading all elements of a web page at once, those that are critical for the initial content display are prioritized. By implementing delay loading, the page load speed is improved, resulting in a better user experience and reduced wait times. This technique is particularly useful on websites that contain images, videos, or scripts that are not immediately visible. By delaying the loading of these elements, the amount of data the browser needs to process initially is reduced, which can lead to a more agile and efficient performance. Additionally, delay loading can contribute to a better score in web performance evaluation tools, such as Google PageSpeed Insights, which can positively influence the site’s SEO. In summary, delay loading is a key strategy in modern web design, focused on optimizing user experience and improving the overall performance of web pages.
History: Delay loading began to gain popularity in the late 2000s as web developers sought ways to improve page load speeds. With the rise of mobile devices and slower internet connections, the need to optimize resource loading became more critical. In 2015, Google introduced delay loading as a best practice in its web development documentation, helping to solidify its use in the industry.
Uses: Delay loading is primarily used on websites that contain heavy multimedia elements, such as images and videos, as well as in web applications that require loading scripts and styles that are not immediately necessary. It is also applied in mobile app development and in creating dynamic user interfaces, where efficiency in resource loading is crucial for user experience.
Examples: A practical example of delay loading is the use of the ‘lazysizes’ library on a website, which allows images to load only when they are about to enter the user’s viewport. Another example is the implementation of delay loading on video platforms like YouTube, where videos do not load until the user clicks on them.
