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Node.js – Timers Module – Scheduling Timers
The timers module contains functions that can execute code after a certain period of time. You do not need to import the timer module explicitly, as it is already globally available across the emulated browser JavaScript API.
Timers module is mainly categorised into two categories
Scheduling Timers − This timer schedules the task to take place after a certain instant of time.
setImmediate()
setInterval()
setTimeout()
Cancelling Timers − This type of timers cancels the scheduled tasks which is set to take place.
ClearImmediate()
clearInterval()
clearTimeout()
Scheduling Timers
1. setTimeout() Method
The setTimeout() method schedules the code execution after a designated number of milliseconds. Only after the timeout has occurred, the code will be executed. The specified function will be executed only once. This method returns an ID that can be used in clearTimeout() method.
Syntax
setTimeout(function, delay, [args])
Example 1
let str = 'TutorialsPoint!'; setTimeout(function () { // Will be printed after 2 seconds return console.log(str); }, 2000); // This will be printed immediately console.log('Executing setTimeout() method');
Output
Executing setTimeout() method TutorialsPoint!
2. setImmediate() Method
setImmediate() executes the code at the end of the current event loop cycle.
Syntax
setImmediate(function, [args])
Example
filename - immediate.js
// Setting timeout for the function setTimeout(function () { console.log('setTimeout() function running'); }, 5000); // Running this function immediately before any other setImmediate(function () { console.log('setImmediate() function running'); }); // Directly printing the statement console.log('Simple statement in the event loop');
Output
Simple statement in the event loop setImmediate() function running setTimeout() function running
3. setInterval() Method
setInterval() executes the code after the specified interval. The function is executed multiple times after the interval has passed. The function will keep on calling until the process is stopped externally or using code after specified time period.
Syntax
setInterval(function, delay, [args])
Example
filename - interval.js
setInterval(function() { console.log('Tutoirals Point - SIMPLY LEARNING !'); }, 1000);
Output
Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING ! Tutoirals Point - SIMPLY LEARNING !
4.clearImmediate() Method
This method clears the Immediate timer object that is created by the setImmediate() method.
Syntax
clearImmediate(timer)
Example
filename - clearImmediate.js
// clearImmediate() Example var timer = setImmediate(function A() { console.log("Timer set"); }); clearImmediate(timer); console.log("Timer cancelled");
Output
Timer cancelled
5.clearInterval() Method
This method clears the Immediate timer object that is created by the setInterval() method.
Syntax
clearInterval(timer)
Example
filename - clearInterval.js
// clearInterval() Example var si = setInterval(function A() { return console.log("Setting Intevals for 500 ms !"); }, 500); // Cleared the interval from 1000 ms setTimeout(function() { clearInterval(si); }, 1000);
Output
Setting Intevals for 500 ms !
6.clearTimeout() Method
This method clears the Immediate timer object that is created by the setTimeout() method.
Syntax
clearTimeout(timerObject)
Example
filename - clearTimeout.js
// clearTimeout() Example var timer = setTimeout(function A() { return console.log("Hello TutorialsPoint!"); }, 500); // timer2 will be executed var timer2 = setTimeout(function B() { return console.log("Welcome to TutorialsPoint!"); }, 500); clearTimeout(timer);
Output
Welcome to TutorialsPoint!