safe-timers

Safe Timers

About

Q: What's this all about? Aren't JavaScript timers safe? A: Long story short: they're a bit broken. This module unbreaks it.

Whether it's by spec, or by accident, all major browsers and Node.js all limit the interval a setTimeout can accept to a 32 bit signed integer. What that means in essence is that a timeout can never last longer than 24.85 days. Long enough, right?

The problem is that:

• In human (non-binary) terms, this is a really arbitrary number.
• In long running processes (whether on the web, or in Node), you are limited.
• If the interval you provide overflows this limit, the timer fires immediately!

All the arguments about "you shouldn't need intervals this big anyway" go out the window the moment you provide a big one and instead of never firing, it fires immediately. This is a real problem. And so here we are, Safe Timers solves this for you.

Does that mean you should forego the browser native setTimeout and setInterval altogether? Absolutely not. Most of the time, we pass constant short intervals, in which case Safe Timers are overkill. But when your interval comes from some variable that depends on state or user input, using Safe Timers is a good idea.

API

Timer setTimeout(Function callback, number interval, mixed arg1, mixed arg2, ...)

Calls callback after at least interval milliseconds have passed. All arguments passed after the interval will be passed to the callback once it gets invoked. Returns a Timer instance.

const setTimeout = require('safetimers').setTimeout;

setTimeout(function (msg) {
  console.log(msg);
}, 5000, 'Hello world');

Timer setTimeoutAt(Function callback, number timestamp, mixed arg1, mixed arg2, ...)

Calls callback when our clock reaches the given timestamp (in milliseconds). All arguments passed after the interval will be passed to the callback once it gets invoked. Returns a Timer instance.

const setTimeoutAt = require('safetimers').setTimeoutAt;

setTimeoutAt(function (msg) {
  console.log(msg);
}, Date.now() + 5000, 'Hello world');

Interval setInterval(Function callback, number interval, mixed arg1, mixed arg2, ...)

Calls callback after at least every interval milliseconds. All arguments passed after the interval will be passed to the callback when it gets invoked. Returns an Interval instance.

const setInterval = require('safetimers').setInterval;

setInterval(function (msg) {
  console.log(msg);
}, 5000, 'Hello world');

timer.clear() / interval.clear()

The response from safetimers.setTimeout[At] and safetimers.setInterval are Timer and Interval objects respectively. To cancel a timer or interval, you can call clear on it.

const setTimeout = require('safetimers').setTimeout;

const timer = setTimeout(function (msg) {
  console.log(msg); // this will never show
}, 5000, 'Hello world');

timer.clear();