jQuery Multidimensional Array (dynamic key) - Cannot set property of undefined

Question

Thanks you Chad for his solution, however it now appears to clear values from the array, here is a foreach on the console log which shows you my situation (followed by the updated code for the update function):

timer.html:60 ------------------------------------
timer.html:57 0
timer.html:58 undefined
timer.html:57 1
timer.html:58 1.910
2timer.html:60 ------------------------------------
timer.html:57 0
timer.html:58 undefined
timer.html:57 1
timer.html:58 undefined
timer.html:57 2
timer.html:58 1.727
2timer.html:60 ------------------------------------
timer.html:57 0
timer.html:58 undefined
timer.html:57 1
timer.html:58 undefined
timer.html:57 2
timer.html:58 undefined
timer.html:57 3
timer.html:58 0.690
timer.html:60 ------------------------------------

=============================================

function updateLap(kartId){

  if (isNaN(driverLapNumber[kartId])) {
     //IF LAP NOT SET THEN THE KART ID NEEDS TO BE SET AS 0 AS IT IS THE START OF THE RACE
     window.driverLapNumber[kartId] = 0;  
  }

  //ADD ONE LAP TO THE KART ID
  driverLapNumber[kartId]++;

  //ADD LAP TIME FOR CURRENT LAP NUMBER  
  driverLapTimes[kartId] = [];
  driverLapTimes[kartId][driverLapNumber[kartId]] = window.lapTime;

   $.each(driverLapTimes , function( index, obj ) {
    $.each(obj, function( key, value ) {
        console.log(key);
        console.log(value);     
    });
    console.log("------------------------------------");
  });


  $(".lapTimes").prepend("kartId: "+kartId+" - "+window.lapTime+"<br>");

}

I suppose I can blame PHP for this as it would be possible with the way I am writing it currently, I need assistance in correcting this please.

Everything is fine except for the SECOND key on the driverLapTimes array, I want it to output something like:

driverLapNumber[999][1] = 6.666;
driverLapNumber[999][2] = 6.666;
driverLapNumber[999][3] = 6.666;
driverLapNumber[999][4] = 6.666;

But the 1,2,3,4 keys are coming up with the following console error:

Uncaught TypeError: Cannot set property '1' of undefined

The function code:

function updateLap(kartId){

  if (isNaN(driverLapNumber[kartId])) {
     window.driverLapNumber[kartId] = 0;  
  }

  //ADD ONE LAP TO THE KART ID
  driverLapNumber[kartId]++;

  //ADD LAP TIME FOR CURRENT LAP NUMBER
  driverLapTimes[kartId][driverLapNumber[kartId]] = window.lapTime;  

}

Can you post some of your data/data structures in driverLapNumber array and driverLapTimes? — mhodges
– mhodges, Commented Sep 28, 2016 at 21:12
Did you initialize driverLapNumber[999] as an Array? driverLapNumber[999] = new Array() — Marcel Dieterle
– Marcel Dieterle, Commented Sep 28, 2016 at 21:15

Chad McGrath · Accepted Answer · 2016-09-28 21:39:04Z

3

In this case it's likely that the array item hasn't been declared as a new array. Try this:

function updateLap(kartId){



if (isNaN(driverLapNumber[kartId])) {
     window.driverLapNumber[kartId] = 0;  
  }

  //ADD ONE LAP TO THE KART ID
  driverLapNumber[kartId]++;

  //ADD LAP TIME FOR CURRENT LAP NUMBER
  if(!driverLapTimes[kartId]){
       driverLapTimes[kartId] = [];
  }
  driverLapTimes[kartId][driverLapNumber[kartId]] = window.lapTime;  

}

Of course you could always put the declaration outside of this loop by creating a method to construct your array before hand.

edited Sep 28, 2016 at 21:39

answered Sep 28, 2016 at 21:14

Chad McGrath

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4 Comments

Peter Bennett Over a year ago

This immediately looked logical and yes it worked, many thanks!

Chad McGrath Over a year ago

Firstly: I'll edit in a quick fix that checks to see if there's something in there. 2nd : If I'm getting you right, then you have values that were in there before, but are cleared from the loop afterward? If that's true, you should consider creating a method that constructs your array before hand, and doesn't declare the 2nd dimension of the loop above.

Peter Bennett Over a year ago

Perfect, many thanks, my jQuery is rusty, and because the script is not going to be that big I am happy with a simple fix :)

Chad McGrath Over a year ago

Happy to help. I know it probably doesn't matter. But since a lap time of 0 is falsey, it will reinitialize the array if a value of 0 is in there, so you'll get an undefined instead of a 0 for the laptime. Just sayin.

CNKR · Accepted Answer · 2016-09-28 21:14:30Z

0

Try as below and let me know

var a = new Array();
a[0]= new Array();
a[0].push(1);
a[0].push(2);
a[0].push(3);

console.log(a[0][0]);
console.log(a[0][1]);
console.log(a[0][2]);

answered Sep 28, 2016 at 21:14

CNKR

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