True Timeout

True Timeout is a Web Worker based utility that gives you the ability to have a timeout that is closest to a True Timeout unlike setTimeout (provided by the browser) that is based on the event loop.

An example can be seen here: https://revanth0212.github.io/true-timeout/

To start using it in your projects,

npm install true-timeout

Motivation

In languages like Java it is possible to have a timeout that is closer to a True Timeout, but when it comes to JavaScript that works on a single thread, true timeout is never achieved.

Current API that does timeout in JavaScript is setTimeout which is provided by the broswer. When you call setTimeout with a callback function and a timeout mentioned in milliseconds, the browser initiates a browser thread that will run the timeout logic and once done, puts the callback function in the JavaScript event loop.

Since the JavaScript engine is single threaded it can only run functions from a single stack. To implement timeout kind of Async operations, JavaScript engine picks up operations form event loop when ever it had nothing to do meaning the stack is empty.

So now setTimeout is dependent on event loop and hence it can only guarantee minimum timeout and not exact timeout.

For instance:

If we run the following in browser, a browser thread will be spawned and it will wait till 3 seconds after which it will put the alert call into the event loop.

setTimeout(function(){ alert("Hello"); }, 3000);

If the event loop already has some events pending, the alert call will stay there till the stack is empty and till all the pending events are addressed.

Solution: trueTimeout

Solution to this is a Worker based solution. True timeout works on a web worker which is also a thread by itself but it does not depend on the event loop.

Usage

window.trueTimeout(trueTimeoutCallBack, timeout, failureHandler)

trueTimeout is injected into global scope so you can start using it just like you would use setTimeout.

failureHandler is optional.

Params

1. callback function which will be called once the timeout expires. Required. () => void
2. timeout in milliseconds. Required. number
3. errorHandler funciton which will be called if there is any error encountered in the whole process. Optional. () => void

Sample

Check out index.html

# Wanna Contribute?

Please fork/branch the project in github and once done create a PR.

To run the project locally for development make sure you have http-server package installed globally.

npm run start