Definition
Lazy loading is a programming technique used in web development to load resources asynchronously onto a web page. In other words, it consists of delaying the loading of certain elements, such as images and videos, until they are really needed.
Specifically, when lazy loading is used, images, videos, and other media are loaded only when the user approaches them while scrolling through the page.
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Benefits of Lazy Loading
Among the benefits of Lazy Loading we can mention the following:
- Improves page load time: By not having to load all the elements of the page at the same time, lazy loading allows faster loading of those elements that the user needs to see immediately. This significantly improves the overall page load time, which in turn can improve the user experience and decrease the bounce rate.
- Reduce bandwidth usage: By loading page elements asynchronously, lazy loading also reduces users’ bandwidth usage, which can be especially useful on slow or expensive connections. If images, videos, or other heavy elements are used, this can make a big difference in page loading speed.
- Decreases battery consumption: On mobile devices, lazy loading can have a big impact on battery life. By reducing the number of items charged at the same time, power consumption is decreased and battery life is extended.
How to lazy load
Implementing lazy loading on a web page is relatively straightforward, although it requires some technical knowledge. Generally speaking, it can be done as follows:
- Identify the elements that will load asynchronously: As mentioned above, lazy loading is usually used for images and videos, but it can also be applied to other elements such as JavaScript or CSS files. In any case, it is important to identify which elements will be loaded on a deferred basis in order to implement the corresponding code.
- Add the necessary JavaScript code: To implement lazy loading it is necessary to use JavaScript code that is responsible for managing the loading of the elements. There are several libraries and plugins that facilitate this task, so it is not necessary to write the code from scratch. Among the most popular options are Lazy Load, Lozad.js or Lazy Load XT.
- Configure the code according to the needs: Once you have chosen the library or plugin to use, it is necessary to configure it according to the needs of our website. This includes things like the loading speed of elements, how they are displayed (for example, with transition effects), or how you define the items to load asynchronously.
- Test the effect on loading speed: Once lazy loading has been implemented, it is important to check that the page load time has indeed been reduced. To do this, you can use tools such as PageSpeed Insights or GTmetrix, which allow you to measure the loading time and the overall speed of the page.
Frequently asked questions about Lazy Loading
What does Lazy Loading mean in digital marketing?
Lazy Loading refers to the concept described in this glossary entry: Definition Lazy loading is a programming technique used in web development to load resources asynchronously onto a web page. In other words, it consists of delaying the loading of certain elements, such as images and videos, until they are really needed. It gives teams a shared vocabulary for analysing digital projects.
When should teams pay attention to Lazy Loading?
Teams should review Lazy Loading when it affects acquisition, measurement, user experience, content, automation or campaign performance. The important step is to connect the definition with a real decision.
How is Lazy Loading used in a digital strategy?
Lazy Loading is used by translating the concept into practical checks: where it appears in the funnel, which data or channel is involved and whether it needs optimisation, monitoring or documentation.
What is a common mistake when interpreting Lazy Loading?
A common mistake is using Lazy Loading too broadly. It is better to verify the context, the tool or the metric involved before making strategic or technical conclusions.