When handling user interactions on web applications—such as typing in search boxes, scrolling, or resizing windows—the default behavior can often lead to unnecessary performance issues. Typically, every single user action triggers a function call, resulting in multiple server requests and creating a sluggish and frustrating user interface.
Two essential techniques, debounce and throttle, help manage these events by controlling how frequently functions execute, significantly improving both performance and user experience.
What is Debounce?
Debounce ensures a function only executes after a certain period of inactivity. It resets its timer with every new action, waiting until the user has stopped interacting before firing the function.
Key Points:
- Waits for user activity to stop before running the function.
- Timer resets with each new input or event.
- Ideal for actions like search inputs, where it’s best to wait until the user finishes typing before sending a server request.
Use Case:
A user typing in a search box triggers multiple calls. Debounce delays the server request until the user has paused their input, minimizing unnecessary requests.
What is Throttle?
Throttle limits the frequency of a function call, ensuring it only executes once within a specified interval, regardless of how many times the event occurs.
Key Points:
- Executes a function at regular, set intervals.
- Function will run at least once per specified time interval.
- Great for actions that trigger continuously, such as scrolling or resizing.
Use Case:
When a user scrolls a page, throttle controls the rate at which scroll events trigger certain functions, like animations or lazy loading, maintaining smooth performance.
Debounce vs. Throttle: Quick Comparison
Debounce is perfect when the function should only execute after user activity has stopped completely.
Throttle is ideal when a function needs to run regularly but not continuously.
By strategically applying debounce and throttle techniques, this significantly improves both user interface responsiveness and overall application performance.
Summary
| Feature | Debounce | Throttle |
|---|---|---|
| When it runs | After a pause | At regular intervals |
| Purpose | Wait for silence | Limit frequency |
| Typical use | Autocomplete, Search input | Scroll, resize, mousemove |
| Behaviour | Fires once after activity ends | Fires at most once per interval |