zero-timeout

setTimeout with true zero delay

Motivation

Like setTimeout, but without the 4 millisecond minimum delay.

Why a timer with no time? The supplied callback will be bumped to the back of the task queue. If other more critical tasks (like user interaction or screen rendering) are already in the queue, they will be allowed to finish first. But if the queue is empty, the setZeroTimeout callback will be executed immediately.

This can be useful for splitting up long-running tasks across frames. See David Baron's blog post for more on the motivation and methodology.

Usage

zero-timeout is provided as an ESM import.

import 'zero-timeout';

Importing the module adds two methods to the global scope.

setZeroTimeout

This method's interface is just like setTimeout but without the delay argument:

var timeoutID = window.setZeroTimeout(function);
var timeoutID = window.setZeroTimeout(function, arg1, arg2, ...);

The returned ID is a positive integer that can be passed to clearZeroTimeout.

clearZeroTimeout

Cancels a timer previously set up by setZeroTimeout. Syntax is similar to clearTimeout:

window.clearZeroTimeout(timeoutID);

If the callback supplied to setZeroTimeout has already executed, or if the ID supplied to clearZeroTimeout is invalid, clearZeroTimeout will silently do nothing.