Difference between throttling and debouncing a function

javascript

event-handling

performance-optimization

best-practices

byAnton Shumikhin·Feb 5, 2025

Implement throttling and debouncing techniques to control the execution frequency of JavaScript functions.

With throttling, a function can only execute once within a predefined interval. This ensures the execution does not exceed a certain rate, making it invaluable when dealing with continuous actions.

// Yo bro, throttle this to execute every 100 milliseconds; keeps it chill
const throttledFunc = _.throttle(() => {/* Put your logic here */}, 100);

In contrast, debouncing causes a function to pause and wait until there are no calls left within a given interval. Ideal for scenarios where premature execution could disrupt functionality, e.g., taking input from a search bar.

// Chill until there's 300ms silence bro; patience is a virtue
const debouncedFunc = _.debounce(() => {/* Apply your logic here */}, 300);

Integrating these concepts into your arsenal can make your JavaScript apps more responsive, efficient, and performant.

Choosing the right approach

The essence lies in utilizing the two techniques properly across various scenarios.

Throttling is beneficial when you need constant responses in regulated intervals. Actions that fire frequently but need restraining fit this perfectly.
On the flip side, debouncing is your go-to for events firing in rapid succession, where the final state matters, not the journey.

Real-world application scenarios

Consider the following use cases where these techniques can shine:

Throttling:
- Games and Animations: Control frame rates to maintain consistent performance regardless of device capabilities.
- Scroll Events: Regulate UI updates during scrolling.
- Rate-limiting API calls: Prevent server overloads.
Debouncing:
- Search Input: Wait for users to finish typing before firing search queries.
- Form Validation: Validate user inputs only after they finish typing.
- Resize Events: Redraw or layout elements only after the user stops resizing the window.

Possible pitfalls and counterstrategies

While integrating, you might encounter a few hiccups like delayed actions or unresponsive interface. Let's look at some countermeasures:

Control function calls: Adjust the timing strategy to execute throttled or debounced functions at the start or end of the delay period.
Unforeseen event reactions: If an action gets ignored due to throttle but is vital, store the last invocation and execute it after the throttle period.
Synchronization across components: Unified throttled/debounced handlers avoid discrepancies between components.

##Apart from the basics

Go beyond the basics with these advanced tactics:

Cancelable calls: Implement functionality to cancel queued function calls when necessary.
Instant first call: Modify debounce to invoke the function immediately upon initial call and then initiate the waiting sequence.
Hybrid strategy: Consider combining both tactics (bounce inputs, throttle API outputs) for more complex scenarios.

DIY throttling and debouncing

Though libraries like Lodash provide ready-to-use functions, understanding the logic behind them can pay off:

Creating your own throttle involves using setTimeout and Date.now() to manage a basic time window.
A custom debounce, on the other hand, could utilize clearTimeout to reset the delay timer when the watched event triggers again.