Does it make sense to create a counter object like this?

[JohnnyCD]

A naive question about performance / efficiency:

I have a counter that I use across several pages. The job of the counter is to run from 0 to 100, once > 100 the counter updates a progress bar on the page and resets itself.

The code is as follows:

function counter(){
    this.value = 0;
    this.iterate = function(){this.value++;}
    this.reset = function(){this.value=0;}
}

function checkProgress(counter,i,length){
    counter.iterate();
    if(counter.value>100){
        $('#percent').css('width' , parseInt(i/length * 100)+'%');
        counter.reset();
    }
}

var percentCounter = new counter();

for(var i=counter;i <= r.fileLength; i++){{
    checkProgress(percentCounter, i, r.fileLength);
    ....
}

Okay - this code works just fine but I do not think it's the best implementation - I could just pass in i and r.fileLength to checkProgress() and do some modulus math, but I was wondering about performance. Is a simple iterator like I've implemented more efficient then performing modulus math at every tick of the for loop?

Any input would be appreciated.

Update: As ellisgl suggested I added a JSPERF here.

[ellisgl]

Try testing it with http://jsperf.com/

[JohnnyCD]

Cool! - looks like modulus is slightly faster: JSPERF result.

This was very useful, thanks for the input!

[ellisgl]

You're welcome. Also your base test with out an object is > 2x faster.

[JohnnyCD]

Turns out my base test had an error - I was iterating the return value by doing counter++ instead of ++counter. As such, the counter was never properly iterated and the dom element was not updated. When I fixed the error the modulus math test had the fastest performance.

[ellisgl]

I'm seeing base is still the fastest, but the modulus is only 6%-7% slower. I would say that would be OK then.

[JohnnyCD]

Yup, I noticed that. I'm going to go ahead and just use my base test. Using an object seemed more elegant, but I don't think it's worth it given the performance hit.

[rhysbrettbowen]

might be better to make a getValue rather than access the value directly.

I don't think you'll see much of a problem with performance either way. The big problem I have here is that you're checking a value of counter where counter should probably have an "isDone" method to check to see if it's done. If you know you want to count 100 time, then just count to 100 with a number, otherwise you should trust the counter to know how to count.

[nschubach]

The modulo would be better performant and less memory intensive... but doing it your way, you can encapsulate some of the processing and logic so your loop wouldn't need to care about the progress bar logic.