Array value 'Undefined' after splitting string?

Question

I am splitting a function that is in format '0:00:00' using the colon. Once I have done this, I am doing some calculations with the separate numbers by saving them to a separate variable. The values where I am trying to access them after the .split function are giving 'undefined' and I am unsure why.

I have tried using replace instead of split, but split is the easier way using less code to do what I want(ability to have the values separated).

This is what my console shows when entering the time vie input box: I think the error is being caused because of the time being updated with each key stroke so to speak instead after the whole time is entered.

calcPace(time, distance){
  var minutes = 0;
  var seconds = 0



  var hms = time+'';   // your input string
  var intDist = distance+'';
  intDist = parseFloat(distance, 10);
  var a = hms.split(':'); // split it at the colons

  // minutes are worth 60 seconds. Hours are worth 60 minutes.
  var totalMinutes = ((+a[0]) * 60) + ((+a[1])) + (+a[2] / 60);

  console.log(a[0]); //gives 'undefined, should be a number 0-6

  var paceValue = totalMinutes / intDist;
  minutes = Math.floor(paceValue);
  seconds = Math.round((paceValue - minutes) * 60);

  console.log(totalMinutes)
  if(seconds < 10) {
        seconds = "0" + seconds;
    }

  var paceValue = minutes+":"+seconds;

  this.setState({
     pace: paceValue//paceValue
  });
}

the function is being called here

handleButtonPress(){
  console.log("pressed");
  this.calcPace(this.time, this.distance);

}

When I print paceValue, the result is NaN:NaN, as well as minutes and seconds. When checking in the array locations after the split, the values are undefined. I need there to be numbers there and the expected output would be something like '5:24' or similar.

OK well what is this.time() in that handleButtonPress() function? — Pointy
– Pointy, Commented May 6, 2019 at 14:54

Vencovsky · Accepted Answer · 2019-05-06 14:54:09Z

1

This error can happen because of these lines

var a = hms.split(':')
...
var totalMinutes = ((+a[0]) * 60) + ((+a[1])) + (+a[2] / 60);
...
minutes = Math.floor(paceValue);
seconds = Math.round((paceValue - minutes) * 60);

If hms.split(':') doesn't return an array with length of 3. a[x] can be undefined.

If you divide undefined by a number, it will return NaN.

So the reason you are getting undefined is that probably hms isn't a string with 3 :
e.g. ('0:00:00').

I recommend you doing some checking and conditionally creating totalMinutes depending of a.

answered May 6, 2019 at 14:54

Vencovsky

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