The **`Timers` module** is a global module that is part of the standard library. `Timers` provide utilities and functions to schedule the execution of blocks of code at a set time.

The `Timer` module provides a `Timeout` class, which is created internally when the `setTimeout()` or `setInterval()` methods return. `Timeout` can be passed to `clearTimeout()` or `clearInterval()` to cancel the scheduled events.

The event loop of Node.js continues to run as long as `Timer` is active. The `Timeout` class provides the `Timeout.ref()` and `Timeout.unref()` methods to control the default behavior of the event loop.

When the `Timout.ref()` method is called, it requests the event loop to continue running as long as `Timeout` is active. If the method is called multiple times, it has no effect.

# Protoype

```
timeout.ref()
```

# Parameters

* None

# Return value

The `Timeout.ref()` method returns a reference to `timeout` of type `Timeout`.

# Code

If we use the `Timeout.unref()` function here, it will request that the event loop become inactive. In this case, there is no other event keeping the event loop running, so it will terminate before the callback to `setTimeout()` is invoked.

const Timeout = setTimeout(function alfa() {
	console.log("Timeout for 1000ms");
}, 1000);

Timeout.unref();
console.log("callback not invoked")

However, if we call `Timeout.ref()` right after the `unref()` call, we request that the event loop remains active. In this case, the event loop will wait for the callback for `setTimeout()` to be invoked.

const Timeout = setTimeout(function alfa() {
	console.log("Timeout for 1000ms");
}, 1000);

Timeout.unref();
console.log("call back will be invoked")
Timeout.ref();

How to use the Timers module ref() in Node.js

Protoype

Parameters

Return value

Code