Improving Web Performance with the Passive Option for Event Listeners
Event listeners are an important part of web development, allowing developers to add functionality to web pages that respond to user input or other events. However, poorly written event listeners can cause performance issues, particularly on mobile devices.
The passive option is a relatively new feature of event listeners in modern browsers that can help improve performance, particularly when handling events such as scrolling or touch interactions. When the passive option is set to true, it indicates to the browser that the event listener will not prevent the default behavior of the event. This allows the browser to continue with the default behavior of the event immediately, without waiting for the event listener to finish executing. This can improve the performance and smoothness of scrolling and other touch-based interactions.
It’s important to note that not all events support the passive option. Events that support the passive option include touchstart, touchmove, touchend, touchcancel, wheel, mousewheel, DOMMouseScroll, and resize. When using the passive option, it's important to only use it for events that support it to avoid errors and ensure expected behavior.
Here’s an example of how to add a scroll event listener with the passive option set to true:
