Accurate Intervals

Provides functions for setting intervals that try to correct themselves to align with the targetted intervals.

Install

npm i jackindisguise/accurate-intervals

Example

Absolute Intervals

Absolute intervals are intervals that try to fire with respect to timestamp 0.

import {setAbsoluteInterval} from "accurate-intervals";
setAbsoluteInterval((delay)=>{
	console.log(`(${Date.now()}: Fired after ${delay} milliseconds.`);
}, 1000);
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If Date.now() returns 123###, setting an absolute interval that fires every 1000 milliseconds should be expected to fire at 124000, 125000, 126000, 127000, etc...

The first time the interval fires, the delay can vary wildly.

• If you set it at timestamp ###999, it will want to fire after 1 millisecond.
• If you set it at timestamp ###001, it will want to fire after 999 milliseconds.

Relative Intervals

Relative intervals are intervals that try to fire with respect to when they were called.

import {setRelativeInterval} from "accurate-intervals";
setRelativeInterval((delay)=>{
	console.log(`(${Date.now()}: Fired after ${delay} milliseconds.`);
}, 1000);
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If Date.now() returns 123###, setting a relative interval that fires every 1000 milliseconds should be expected to fire at 124###, 125###, 126###, 127###, etc...

Due to inherent unpredictability in the way intervals and timeouts work, the time between firing will vary, but it will always be between 0ms~1000ms (in this example). In my experience, you can expect it to vary by 0ms~30ms on average regardless of the actual interval assigned, with some spikes of 100ms~ or more uncommonly.

Cycle Skipping

Setting an interval below 30ms is inadvisable in pretty much all circumstances, as you may create a runaway condition where your interval will have to endlessly try to catch up.

In order to avoid this scenario, these interval functions automatically skip cycles that are trying to catch up.

Canceling intervals.

import {setRelativeInterval, clearCustomInterval} from "accurate-intervals";
const intervalID = setRelativeInterval((delay)=>{
	clearCustomInterval(intervalID);
	console.log("only fires once");
}, 1000);
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clearCustomInterval clears intervals set by both setRelativeInterval and setAbsoluteInterval.

Supports CJS and ESM

CJS

const {setAbsoluteInterval} = require("accurate-intervals");
setAbsoluteInterval((delay)=>{
	console.log(`(${Date.now()}: Fired after ${delay} milliseconds.`);
}, 1000);
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ESM

import {setAbsoluteInterval} from "accurate-intervals";
setAbsoluteInterval((delay)=>{
	console.log(`(${Date.now()}: Fired after ${delay} milliseconds.`);
}, 1000);
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