timers

All the timing functions you need - for Deno and the browser.

Installation

Just import it directly from the https://deno.land/x/
registry

import {
  delay,
  setInterval,
  setTimeout,
  times,
} from "https://deno.land/x/timers@v0.2.0/mod.ts";

Features

long timeouts and intervals

With every function timers exports, it is possible to have a timeout or interval that is longer than 24.8 days (2^31-1 milliseconds).

If you need only this functionality, timers exports the functions setTimeout, setInterval, clearTimeout and clearInterval.

They are almost completely compatible with the Web API’s functions, but it is not allowed to pass a string as function argument to one of them.

Important Note

You can’t use the native functions mixed with the functions exported by this module! So, if you import setTimeout, you should import clearTimeout as well, as the native function won’t clear the timeout!

import {
  clearInterval,
  clearTimeout,
  setInterval,
  setTimeout,
} from "https://deno.land/x/timers@v0.2.0/mod.ts";

const timeout = setTimeout(() => {
  console.log("in 30 days");
}, 1000 * 60 * 60 * 24 * 30);

const interval = setInterval(() => {
  console.log("every 30 days");
}, 1000 * 60 * 60 * 24 * 30);

// Clear them
clearTimeout(timeout);
clearInterval(interval);

Tip

If you don’t want the native functions overwritten, setTimeout and setInterval are exported as setLongTimeout and setLongInterval as well. This also applies to clearTimeout and clearInterval. Also you can at any time use globalThis.setTimeout, which applies to the other functions as well

import {
  clearLongInterval,
  clearLongTimeout,
  setLongInterval,
  setLongTimeout,
} from "https://deno.land/x/timers@v0.2.0/mod.ts";

time strings

With each function expect setInterval and setTimeout, that timers exports, it is possible to use a time string as delay argument instead of the number of milliseconds. For example:

import { every } from "https://deno.land/x/timers@v0.2.0/mod.ts";

every("1minute").do(() => {
  console.log(new Date().toLocaleTimeString());
});

supported format

• ms, millisecond, milliseconds
• s, sec, secs, second, seconds
• m, min, mins, minute, minutes
• h, hour, hours
• d, day, days

Examples

• 2 days, 5 hours and 2 minutes
• 3sec, 2ms
• 5mins3secs

delay

timers exports the function delay. The API is like the delay function from deno’s std library, but it returns an AbortablePromise, so you can abort the promise with calling abort() on it. It has two options:

• signal: An AbortSignal that aborts the timeout. The delay function will reject.
• persistent (only available in Deno): Indicates whether the process should continue to run as long as the timer exists. This is true by default.

import { delay } from "https://deno.land/x/timers@v0.2.0/mod.ts";
const MSG = "Please type your name";
const info = document.querySelector("p.info");
const nameInput = document.querySelector("input.name");
const abort = new AbortController();
const { signal } = abort;

nameInput.addEventListener("input", () => abort.abort(), { once: true });

await delay(2000, {
  signal,
});

info.textContent = MSG;

times

Another function timers provides is times. It is basically like setInterval, but executes the interval just a certain number of times. Like with delay, you have the signal and persistent (only available in Deno) options, plus the silent (supresses errors in the callback) and the args option. Instead of passing the args as rest parameter, like with setInterval, you must pass them as array, in order to have the other options.

import { times } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const paragraph = document.querySelector("p.numbers");
const abortBtn = document.querySelector("button.abort");
const abort = new AbortController();
const { signal } = abort;

abortBtn.addEventListener("click", () => abort.abort(), { once: true });

let i = 0;
times(
  () => {
    paragraph.textContent += `${i}, `;

    i++;
  },
  200,
  20,
  {
    signal,
  },
);

every

every is syntactical sugar over an Interval. The function returns an Every class instance. To start the interval, you call do() with your callback. To set how often the callback should get executed, call limit() on it, but only before you call do(). Calling stop() aborts the interval. It supports the following options:

• signal
• persistent
• args
• silent

import { every } from "https://deno.land/x/timers@v0.2.0/mod.ts";

every("1min").limit(60).do(() => {
  console.log(new Date().toLocaleTimeString());
});

after

after is like every, but for timeouts. It does, of course, not have the limit function, since it gets only executed once. The following options are available:

• signal
• persistent
• args
• silent

import { every } from "https://deno.land/x/timers@v0.2.0/mod.ts";

after("1min").do(() => {
  console.log(new Date().toLocaleTimeString());
});

pTimeout

Adapted from p-timeout Timeout a promise after a specified amount of time.

import { delay, pTimeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const delayedPromise = delay(500);

await pTimeout(delayedPromise, 50);

// => [TimeoutError: Promise timed out after 50 milliseconds]

The function expects at least two arguments:

• promise: A Promise or a function returning a Promise
• delay: The time in milliseconds after which the function rejects
• options (not required):
  • signal: An AbortSignal to abort the function even before it rejects
  • fallbackFn: Do something other than rejecting with an error on timeout. You could for example retry.
  • failMessage: A custom error message. Default: 'Promise timed out after 50 milliseconds'
  • failError: Specify a custom Error. It’s recommended to sub-class of TimeoutError.

It returns a decorated Promise, which can be aborted with its abort() method.

Using with a function

Instead of passing a Promise directly, you can pass a function that retuns a Promise:

import { pTimeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const pingApi = () => fetch("/api");

await pTimeout(pingApi, "50 ms");

The function can take an AbortSignal as parameter as well, which abort event fires, when the timeout times out:

import { pTimeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const pingApi = (signal) => fetch("/api", { signal });

await pTimeout(pingApi, 50);

pTimeout also passes down the signal it got:

import { delay, pTimeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const abort = new AbortController();
const { signal } = abort;

const pingApi = (signal) => fetch("/api", { signal });

pTimeout(pingApi, "100milliseconds", { signal });

delay(50).then(() => abort.abort());

timeout and interval

timeout and interval are like setTimeout and setInterval, but are typed, support time strings meaning that the args option’s type must equal the type of the argument expected by the callback. and supports these options:

• signal
• persistent (only available in Deno)
• args
• times (only interval)

import { interval, timeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const timeout = timeout(() => {
  console.log("in 30 days");
}, "30 days");

const interval = setInterval(() => {
  console.log("every 30 days");
}, "30 days");

// Clear them
clearTimeout(timeout);
clearInterval(interval);

Timeout and Interval classes

Under the hood, all of the functions listed above use the Timeout and Interval classes.
They are exported as well and you can use them to create timeouts without
running them directly.

import { Timeout } from "https://deno.land/x/timers@v0.2.0/mod.ts";

const notifyBtn = document.querySelector("button.notify");
const timeout = new Timeout(() => {
  console.log("hello world");
}, 1000);

// WARNING: running a timeout two times will throw an error
notifyBtn.addEventListener("click", () => timeout.run(), { once: true });

For Timeout, the following options are available:

• signal
• persistent (only available in Deno)
• silent
• args
• times (only for Interval)

Properties

• id: The Id of the timer, can be used with clearTimeout and clearInterval
• aborted: A Promise, that resolves, when the timer gets aborted, but only, if the abort happens with a call of the abort method or the abortion via an AbortController.
• isAborted: A boolean indicating whether the timer has been aborted
• persistent (only available in Deno): A boolean indicating whether the process should continues running as long as the timer exists. This is true by default.
• deprecated: timer: The Id of the timer. Use id instead.
• ran: A boolean indicating whether the timer ran already. Gets only set to true on Interval when the times option has been passed and the interval has run times times.
• running: A boolean indicating whether the timeout is currently running

Interval only

• runs: A number representing the amount of times the interval has run since now

Methods

• run(): runs the timeout and returns the timeout’s id
• abort(reason?: any): aborts the timeout
• unref(): makes the process not continue to run as long as the timer exists
• ref(): makes the process continue to run as long as the timer exists

NOTE

It is not possible to use Deno.unrefTimer() or Deno.refTimer() directly with the id returned by setInterval or setTimeout

Running Tests

To run tests, clone the repository, and run the following command

deno test

or, without cloning

deno test https://deno.land/x/timers@v0.2.0/test.ts

Contributing

Contributions are always welcome!

You found a bug or have an idea about a function, that is not yet implemented in this module?
Feel free to open an issue or a PR!

License

MIT