Lazy loading is a technique used to defer the loading of non-critical resources (such as images, scripts, or content) until they are needed. Instead of loading all resources upfront when the page loads, lazy loading delays the loading process until the user requests or interacts with the specific content.
❓ How is it used?
Lazy loading is implemented using JavaScript to detect when elements enter the viewport or when certain conditions are met (e.g., user scrolling). When triggered, the JavaScript code dynamically loads the resources, typically via AJAX requests or by dynamically adding <script> or <img> tags to the DOM.
Why is it needed?
Lazy loading can significantly improve page load times and reduce initial page weight, especially for pages with large images or extensive content. By deferring the loading of non-essential resources, lazy loading prioritizes the loading of critical content, resulting in a faster and smoother user experience.
Examples:
Lazy loading images in a photo gallery: Images are loaded only when they are about to come into view as the user scrolls down the page.
Lazy loading JavaScript libraries: External JavaScript libraries are loaded only when a specific feature that requires them is activated by the user.
Debouncing:
🔍 What is it?
Debouncing is a technique used to limit the rate at which a particular function is executed, especially in response to rapid or frequent events like scrolling, resizing, or typing. It prevents the function from being called multiple times in quick succession, ensuring that it is only executed after a specified delay has passed since the last invocation.
❓ How is it used?
Debouncing is typically implemented using a timer mechanism. When the event is triggered, a timer is started with a delay value. If the event is triggered again before the timer expires, the previous timer is canceled, and a new timer is started. The function is executed only after the timer has elapsed without further events.
Why is it needed?
Debouncing is needed to optimize performance and prevent unnecessary or excessive function calls in response to rapid events. Without debouncing, functions like event handlers or API requests may be invoked too frequently, leading to performance issues or unintended behavior.
Examples:
Debouncing the window resize event: When the user resizes the browser window, a function to adjust the layout or perform calculations is invoked only after the user has finished resizing, preventing unnecessary reflows or recalculations during rapid resizing.
Debouncing the input event on a search field: When the user types in a search field, the search function is invoked only after the user pauses typing for a specified period, preventing the search function from being called for every keystroke.