Debouncing vs Throttling in JavaScript: When to Use What?

on

 When working with event-driven programming in JavaScript, optimizing performance is crucial. Debouncing and Throttling are two key techniques used to control how frequently a function executes in response to high-frequency events like scrolling, resizing, or typing. In this blog, we'll explore the differences between these techniques, their use cases, and when to use each.

 

What is Debouncing?

Debouncing ensures that a function is executed only after a specified delay following the last event trigger. It helps in reducing the number of function calls, making it ideal for scenarios where we need to wait until the user stops performing an action.

Example of Debouncing in JavaScript

function debounce(func, delay) {
  let timer;
  return function (...args) {
    clearTimeout(timer);
    timer = setTimeout(() => func.apply(this, args), delay);
  };
}

const handleInput = debounce(() => {
  console.log("Fetching search results...");
}, 300);

document.getElementById("search").addEventListener("input", handleInput);

Use Cases for Debouncing

  • Search input fields: Avoid making API calls on every keystroke.

  • Window resize event: Prevent excessive function execution.

  • Form validation: Execute validation logic only after the user stops typing.

What is Throttling?

Throttling limits the execution of a function to at most once every specified time interval, ensuring that it executes at regular intervals regardless of how frequently the event occurs.

Example of Throttling in JavaScript

function throttle(func, interval) {
  let lastTime = 0;
  return function (...args) {
    const now = Date.now();
    if (now - lastTime >= interval) {
      func.apply(this, args);
      lastTime = now;
    }
  };
}

const handleScroll = throttle(() => {
  console.log("User is scrolling...");
}, 1000);

document.addEventListener("scroll", handleScroll);

Use Cases for Throttling

  • Scroll events: Run functions at controlled intervals during scrolling.

  • Button click handling: Prevent users from repeatedly clicking a button.

  • API polling: Limit API requests to a fixed interval.

 

Key Differences: Debouncing vs Throttling


When to Use What?

Use debouncing when you want to delay execution until a user stops performing an action (e.g., typing in a search bar).

Use throttling when you want to execute a function at a controlled rate, even if the event keeps triggering (e.g., handling scroll events smoothly).

 

Conclusion

Understanding Debouncing vs Throttling in JavaScript is crucial for optimizing event-driven applications. While debouncing ensures that a function runs only after a period of inactivity, throttling ensures that a function runs at a fixed interval. Choosing the right technique depends on your specific use case.