Create a unique function name on the fly for shared timer

Question

I'll start with the exact nature of the problem and then give some background. I am trying to name a function -threadTimer- and give it a random unique identifier, such as 'threadTimer'+ID. A randomly generated ID would work fine. Then, I need to use setInterval on it, to make it fire repeatedly and therein lies my coding problem. I have tried every variation of new, function, function as an object and I just can't get my head around it. You'll notice that the function I have created is an object and perhaps this is where I'm going in circles.

OK, the background I mentioned. threadTimer is fired by a master timer co-ordinating several threads. That's why you'll see I have generated a 'global' object for reference elsewhere. similar HTML entities can fire threadTimer at the same time, hence my requirement to make each instance unique.

window['GlblThreadExe'+ID]=setInterval(function(){threadTimer(elid,parent,lft,top,diameter,point,bStyle,color,grp,startTime,size,ID,counter,div,divwth,divht,wthIncrement,htIncrement,lftStart,topStart,lftIncrement,topIncrement)},interval);

function threadTimer(elid,parent,lft,top,diameter,point,bStyle,color,grp,startTime,size,ID,counter,div,divwth,divht,wthIncrement,htIncrement,lftStart,topStart,lftIncrement,topIncrement){
    // more code
}

In truth, I think its the volume of parameters that I'm passing that's confusing my syntax. Any help appreciated

The `setInterval` will itself return a unique ID. Why does the _variable_ need to have a unique ID, exactly? I'm concerned perhaps the question you are asking is related to a less than ideal approach, and if we understood your requirements perhaps a better solution is available. — Alexander Nied, Oct 25 '19 at 15:08
what is your goal: to have a different implementation for each ['threadTimer'+ID]? or to give to your threadTimer the id which corresponds to the setInterval it comes from? — grodzi, Oct 25 '19 at 15:39
@AlexanderNied. Thanks for your reply. Could you explain more about how setInterval generates a unique id please? I did not know that. I have experiences of the same function calling itself at faster and faster increments because it was before I started uniquely identifying the interval as an object. — gleddersDotcom, Oct 26 '19 at 10:27
@user753642 Yes is the simple answer. Imagine objects on a 'page' animating in this instance. However I have had this problem before and I am looking for a general solution. Thanks for your reply. — gleddersDotcom, Oct 26 '19 at 10:30

score 1 · Accepted Answer · answered Oct 25 '19 at 16:04

Avoid polluting window

Generally instead of polluting the global namespace you can store your setInterval ids in some variable

let intervalIds = {}
intervalIds['GlblThreadExe'+ID] = setInterval(function()...)

If really necessary, then store intervalIds to window

window.intervalIds = intervalIds;

Wrap your anonymous function

When you create the "clock", do not call setInterval directly: Here, createTimerWithId will return a function which calls threadTimer

Dirty id generation

Use a timestamp, and mix it with some random stuff. Or better use a UUID

setInterval(createTimerWithId(), 1000)
function createTimerWithId(){

    let id = Date.now()+Math.random(); //no lib, oneliner. good enough to debug

    return function(){//the same function you gave to setInterval in your example
        threadTimer(id, ...)
    }
}

We can do better

In 1. we generated an id on the fly and thus

your code is not testable (id will always change(well except if you mock Math and Date...)).
your id is ugly (a float...)
it will be hard to know from which setInterval you come from

instead, give it the ID.

function createTimerWithId(ID){

    return function(){//the same function you gave to setInterval in your example
        threadTimer(ID, ...)
    }
}

window['..'+ID] = setInterval(createTimerWithId(ID));

shorter version being

window['..'+ID] = setInterval((id=>{
    return function(){
        threadTimer(id, ...)
    }
})(ID),1000);

That is a really neat solution that had never even occurred to me. Really clever. That solves more issues than just this one too. Many thanks. — gleddersDotcom, Oct 26 '19 at 10:40
Without taking away from the answer, I knew my use of 'global' variables would get spotted here. My solution to the global variables issue is something that I bring from VB and php experience. To progress, I sometimes feel the need to break a few rules. :) — gleddersDotcom, Oct 26 '19 at 10:44

Create a unique function name on the fly for shared timer

1 Answers1

Avoid polluting window

Wrap your anonymous function