doc: unify and dedupe returned values in timers.md

PR-URL: #20310
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>

doc/api/timers.md

@@ -28,7 +28,7 @@ functions that can be used to control this default behavior.
added: v9.7.0
-->

* Returns: {Immediate}
* Returns: {Immediate} a reference to `immediate`

When called, requests that the Node.js event loop *not* exit so long as the
`Immediate` is active. Calling `immediate.ref()` multiple times will have no
@@ -37,22 +37,18 @@ effect.
By default, all `Immediate` objects are "ref'ed", making it normally unnecessary
to call `immediate.ref()` unless `immediate.unref()` had been called previously.

Returns a reference to the `Immediate`.

### immediate.unref()
<!-- YAML
added: v9.7.0
-->

* Returns: {Immediate}
* Returns: {Immediate} a reference to `immediate`

When called, the active `Immediate` object will not require the Node.js event
loop to remain active. If there is no other activity keeping the event loop
running, the process may exit before the `Immediate` object's callback is
invoked. Calling `immediate.unref()` multiple times will have no effect.

Returns a reference to the `Immediate`.

## Class: Timeout

This object is created internally and is returned from [`setTimeout()`][] and
@@ -70,22 +66,20 @@ control this default behavior.
added: v0.9.1
-->

* Returns: {Timeout}
* Returns: {Timeout} a reference to `timeout`

When called, requests that the Node.js event loop *not* exit so long as the
`Timeout` is active. Calling `timeout.ref()` multiple times will have no effect.

By default, all `Timeout` objects are "ref'ed", making it normally unnecessary
to call `timeout.ref()` unless `timeout.unref()` had been called previously.

Returns a reference to the `Timeout`.

### timeout.unref()
<!-- YAML
added: v0.9.1
-->

* Returns: {Timeout}
* Returns: {Timeout} a reference to `timeout`

When called, the active `Timeout` object will not require the Node.js event loop
to remain active. If there is no other activity keeping the event loop running,
@@ -96,8 +90,6 @@ Calling `timeout.unref()` creates an internal timer that will wake the Node.js
event loop. Creating too many of these can adversely impact performance
of the Node.js application.

Returns a reference to the `Timeout`.

## Scheduling Timers

A timer in Node.js is an internal construct that calls a given function after
@@ -113,9 +105,10 @@ added: v0.9.1
* `callback` {Function} The function to call at the end of this turn of
  [the Node.js Event Loop]
* `...args` {any} Optional arguments to pass when the `callback` is called.
* Returns: {Immediate} for use with [`clearImmediate()`][]

Schedules the "immediate" execution of the `callback` after I/O events'
callbacks. Returns an `Immediate` for use with [`clearImmediate()`][].
callbacks.

When multiple calls to `setImmediate()` are made, the `callback` functions are
queued for execution in the order in which they are created. The entire callback
@@ -155,10 +148,9 @@ added: v0.0.1
* `delay` {number} The number of milliseconds to wait before calling the
  `callback`.
* `...args` {any} Optional arguments to pass when the `callback` is called.
* Returns: {Timeout}
* Returns: {Timeout} for use with [`clearInterval()`][]

Schedules repeated execution of `callback` every `delay` milliseconds.
Returns a `Timeout` for use with [`clearInterval()`][].

When `delay` is larger than `2147483647` or less than `1`, the `delay` will be
set to `1`.
@@ -174,10 +166,9 @@ added: v0.0.1
* `delay` {number} The number of milliseconds to wait before calling the
  `callback`.
* `...args` {any} Optional arguments to pass when the `callback` is called.
* Returns: {Timeout}
* Returns: {Timeout} for use with [`clearTimeout()`][]

Schedules execution of a one-time `callback` after `delay` milliseconds.
Returns a `Timeout` for use with [`clearTimeout()`][].

The `callback` will likely not be invoked in precisely `delay` milliseconds.
Node.js makes no guarantees about the exact timing of when callbacks will fire,