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Node.js Timers Complete Reference

Last Updated : 23 Jul, 2025
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Node.js Timers module in Node.js contains various functions that allow us to execute a block of code or a function after a set period of time. The Timers module is global, we do not need to use require() to import it.

Example:

JavaScript 
// Node.js program to demonstrate the
// Immediate Class methods

// Setting Immediate by setImmediate Method
const Immediate = setImmediate(function alfa() {
    console.log("0.>", 12);
});

// Printing Immediate.hasRef method
console.log("1.>", Immediate.hasRef());
// Returns true

// Printing Immediate.ref before unref
console.log("2.>", Immediate.ref());
// Returns timer reference

// Printing Immediate.unref method
console.log("3.>", Immediate.unref());
// Returns Immediate reference and
// sets hasRef to false

// Printing Immediate.hasRef before unref
console.log("4.>", Immediate.hasRef());
// Returns false

// Clears setInterval Immediate
clearImmediate(Immediate);

// Prints after clearing Immediate
console.log("5.>", 2);

Output:

1.> true
2.> Immediate {
  _idleNext: null, ……, [Symbol(triggerId)]: 1
}
3.> Immediate {
 _idleNext: null, ……, [Symbol(triggerId)]: 1
}
4.> false
5.> 2

The Complete List of Timers is listed below:

Node.js Timers Class

Description

Immediate Timer ClassImmediate Class has an object (setImmediate()) which is created internally to scheduled actions, and (clearImmediate()) can be passed in order to cancel those scheduled actions.
Timeout Timer ClassTimeout Class has an object (setTimeout()/setInterval()) which is created internally for scheduled actions, and (clearTimeout()/clearInterval()) can be passed in order to cancel those scheduled actions.

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