Underscore debounce vs vanilla Javascript setTimeout

Question

I understand that debounce in Undercore.js returns a function that will postpone its execution until the wait time is over.

My question is, is there an adva

Answer 1

You can also implement your own debounce in vanilla JavaScript. A widely quoted article is David Walsh's article on function debouncing with underscore which includes the source code used by underscore in their implementation:

// Returns a function, that, as long as it continues to be invoked, will not
// be triggered. The function will be called after it stops being called for
// N milliseconds. If `immediate` is passed, trigger the function on the
// leading edge, instead of the trailing.
function debounce(func, wait, immediate) {
    var timeout;
    return function() {
        var context = this, args = arguments;
        var later = function() {
            timeout = null;
            if (!immediate) func.apply(context, args);
        };
        var callNow = immediate && !timeout;
        clearTimeout(timeout);
        timeout = setTimeout(later, wait);
        if (callNow) func.apply(context, args);
    };
};

The debounce function serves as a generator for the actual function you'd like to call, that way the state can be persisted inside of the closure like this:

// example function
let sayHello = (name) => console.log(`Hi ${name}`)

// generate a debounced version with a min time between calls of 2 seconds
let sayHelloDebounced = debounce(sayHello, 2000)

// call however you want
sayHelloDebounced('David')

Demo in Stack Snippets

function debounce(func, wait, immediate) {
	var timeout;
	return function() {
		var context = this, args = arguments;
		var later = function() {
			timeout = null;
			if (!immediate) func.apply(context, args);
		};
		var callNow = immediate && !timeout;
		clearTimeout(timeout);
		timeout = setTimeout(later, wait);
		if (callNow) func.apply(context, args);
	};
};

let sayHello = (name) => console.log(`Hi ${name}`)

let sayHelloDebounced = debounce(sayHello, 2000)

sayHelloDebounced('David')
sayHelloDebounced('David')
sayHelloDebounced('David')

Other Implementations

• Underscore Docs | Underscore Source
• Lodash Docs | Lodash Source
• 30 Seconds of Code