innerHTML in function (Global variables?)

Question

I'm struggling to get this working. The dispatch() function seems to be getting triggered (tested with the alert), but the innerHTML lines don't seem to work.

Also, i doesn't seem to increase despite the i++ in the onSubmit.

Here is the function in question:

function dispatch(passengers,i,timesArray)
{
    alert('value of i is '+i);
    timesArray[i]=getTime();
        
    var avTime=getAverageTime(timesArrary);
        
    var throughput=passengers*3600000/avTime;
        
    if(i==0)
    {
        document.getElementById('output').innerHTML = 'Calculating...';
    }
    else
    {
        document.getElementById('output').innerHTML = throughput;
    }
    //and possibly a list (w/e)
}

And here is the form:

<form method="post" action="javascript:void(0);" name="applesForm" onSubmit="dispatch(document.applesForm.numPassengers.value, num, times);i++;">
    <input type="text" name="numApples" id="numPassengers" />
    <br/>
    <input type="submit" name="Submit" value="Press on Dispatch!"/>
</form>

Could this be a question of not being able to change global variables from inside the function?

Or, is there something wrong with the avTime or throughput lines which is making the function cease?

Your code contains a typo, timesArrary, which will cause the execution of the function to cease. Is the typo present in the actual copy of the code? — Stephen Booher
– Stephen Booher, Commented Aug 31, 2012 at 20:20
You might try walking the alert through your function, and seeing where it fails. — S. Albano
– S. Albano, Commented Aug 31, 2012 at 20:24
Thanks, the typo is gone. The function seems to be failing at timesArray[i]=getTime();, would this line not successfully change times[num]? — Jess
– Jess, Commented Aug 31, 2012 at 20:47

Teemu · Accepted Answer · 2012-08-31 20:33:39Z

2

In this line:

<form method="post" action="javascript:void(0);" name="applesForm" onSubmit="dispatch(document.applesForm.numPassengers.value, num, times);i++;">

i is a global variable, but in dispatch() i is an argument which is not in global scope. Inside dispatch() it is in local scope of that function, and can't be increased in global scope. Hence I think your onSubmit()should be:

onSubmit="dispatch(document.applesForm.numPassengers.value, num, times);num++;">

edited Aug 31, 2012 at 20:33

answered Aug 31, 2012 at 20:28

Teemu

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8 Comments

Jess Over a year ago

Thank you, i should only exist inside the function. But it's still failing.

Teemu Over a year ago

Try to return false from dispatch() to prevent actual submit of the form.

Jess Over a year ago

Added return false though that wasn't the ultimate problem.

Teemu Over a year ago

Still fails? So we'd like to see the code for getAverageTime() and getTime(), maybe the truth is in those functions :).

Collin Grady Over a year ago

You appear to be mixing solutions - you're passing "num" into the function call, using "i" inside the function, but you added "i++" to the onsubmit instead of "num++" (though if it's global, one wonders why you're passing it into the function at all)

|

Apoc · Accepted Answer · 2012-08-31 21:33:29Z

Why is the variable being increased outside the function? Shouldn't it be inside the function and increased there?

Also, if num is global, you don't need to pass it as a parameter.

// global
var num = 0;

function dispatch(passengers, timesArray)
{
    alert('value of num is ' + num);
    timesArray[num]=getTime();

    var avTime = getAverageTime(timesArrary);

    var throughput = passengers * 3600000 / avTime;

    if(num == 0)
    {
         document.getElementById('output').innerHTML = 'Calculating...';
    }
    else
    {
        document.getElementById('output').innerHTML = throughput;
    }
    //and possibly a list (w/e)

    // increasing num here!
    num++;
}

Then your form could drop the increase in the variable, and the num from the call.

<form method="post" action="javascript:void(0);" name="applesForm" onSubmit="dispatch(document.applesForm.numPassengers.value, times)">

Cheers, Apoc.

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