Node.js — Timers

setTimeout

setTimeout(() => {
    console.log('Executed after 1 second');
}, 1000);

const id = setTimeout(fn, delay);
clearTimeout(id); // Cancel

setInterval

let count = 0;
const interval = setInterval(() => {
    count++;
    console.log(`Count: ${count}`);
    if (count >= 5) clearInterval(interval);
}, 1000);

setImmediate

setImmediate(() => {
    console.log('Executes after current event loop');
});

process.nextTick

process.nextTick(() => {
    console.log('Executes before next event loop');
});

Timer Comparison

Function	When it runs
setTimeout(fn, 0)	Next event loop iteration
setImmediate(fn)	After I/O callbacks
process.nextTick(fn)	Before next event loop

Practical Example

// Debounce
function debounce(fn, delay) {
    let timer;
    return function(...args) {
        clearTimeout(timer);
        timer = setTimeout(() => fn(...args), delay);
    };
}

// Throttle
function throttle(fn, limit) {
    let inThrottle;
    return function(...args) {
        if (!inThrottle) {
            fn(...args);
            inThrottle = true;
            setTimeout(() => inThrottle = false, limit);
        }
    };
}

Mini Practice

1. Use setTimeout for delays
2. Use setInterval for intervals
3. Cancel a timer
4. Implement debounce

Up Next

Continue with Processes — managing child processes.