Using Node.js Timers: Scheduling Code Execution with `setTimeout()` and `setInterval()`

Learn how to use Node.js's built-in timer functions (`setTimeout()` and `setInterval()`) to schedule code execution after a specified delay or at regular intervals. This tutorial provides clear examples and explains how to manage timers effectively for creating dynamic and responsive applications.

Node.js Timers

Node.js provides global timer functions that don't require the `require()` statement. These functions allow you to schedule code execution after a specified delay or at regular intervals.

Timer Functions

Node.js offers these timer functions:

Setting Timers

• setImmediate(): Executes a callback function after the current event loop iteration completes.
• setInterval(): Repeatedly executes a callback function at a specified interval (in milliseconds).
• setTimeout(): Executes a callback function once after a specified delay (in milliseconds).

Clearing Timers

• clearImmediate(immediateObject): Cancels a timer set by setImmediate().
• clearInterval(intervalObject): Cancels a timer set by setInterval().
• clearTimeout(timeoutObject): Cancels a timer set by setTimeout().

Example: setInterval()

This example prints a message every 1000 milliseconds (1 second):

setInterval(function() {
    console.log("setInterval: Hey! 1 second completed!..");
}, 1000);
            

Run this with node timer1.js. The script will continue running until you manually stop it.

Here's another example that increments a counter every second:

var i = 0;
console.log(i);
setInterval(function() {
    i++;
    console.log(i);
}, 1000);
            

Example: setTimeout()

This example prints a message after a 1-second delay:

setTimeout(function() {
    console.log("setTimeout: Hey! 1 second completed!..");
}, 1000);
            

Run with node timer1.js. The message is printed once after the delay.

This example uses recursion to repeatedly call setTimeout:

var recursive = function() {
    console.log("Hey! 1 second completed!..");
    setTimeout(recursive, 1000);
};
recursive();
            

Example: Using clearTimeout() and clearInterval()

These examples demonstrate canceling timers:

function welcome() {
    console.log("Welcome to JavaTpoint!");
}
var id1 = setTimeout(welcome, 1000);
var id2 = setInterval(welcome, 1000);
clearTimeout(id1); // Cancel setTimeout
// clearInterval(id2); //Uncomment to cancel setInterval
            

function welcome() {
    console.log("Welcome to JavaTpoint!");
}
var id1 = setTimeout(welcome, 1000);
var id2 = setInterval(welcome, 1000);
// clearTimeout(id1); //Uncomment to cancel setTimeout
clearInterval(id2); // Cancel setInterval
            

next →

← prev