Ytukyg

I'm doing a project, and this function returns NaN. The last time I had this problem, I fixed it by defining a variable that was equal to 0. However it doesn't work.

var avstandArray = [

  [0, 62.3, 58.8, 44.6, 33.2],

  [62.3, 0, 37.9, 65.3, 60.1],

  [58.8, 37.9, 0, 40.5, 78.5],

  [44.6, 65.3, 40.5, 0, 77.6],

  [33.2, 60.1, 78.5, 77.6, 0]

]



var reiserute = [0, 1];



function ruteFunction() {

  var z = 0;

  for (var i = 0; i < reiserute.length; i++) {

    z += avstandArray[reiserute[i]][reiserute[i + 1]];

  }

  return z;

}



console.log(ruteFunction());

The head of your loop is as follows:

for (var i = 0; i < reiserute.length; i++)

This means that i will vary from 0 up to reiserute.length - 1, inclusive.

Then, in your loop body, you do this:

z += avstandArray[reiserute[i]][reiserute[i + 1]];

Note in particular the reiserute[i + 1]. Since i is running from 0 to reiserute.length - 1, i + 1 will range from 1 to reiserute.length. So on the last iteration you are trying to access reiserute[reiserute.length]. And this will be undefined - you are trying to access an index "one beyond" the end of the array.

So you are then evaluating

avstandArray[reiserute[i]][undefined]

which is itself undefined. Then += forcibly coerces this to a Number, which is where your NaN comes from.

While I'm not sure what the exact intention behind your code is, the easiest fix would be to change the header of your loop to not access elements beyond the last in the array. That is, do this instead:

for (var i = 0; i < reiserute.length - 1; i++)

The problem is that

z+= avstandArray[reiserute[i]][reiserute[i+1]];

the above code will try to get the value from reiserute array at n+1th element which is undefined and adding the undefined element to number will throw NaN exception. So Change the logic accordingly.

for (var i = 0; i < reiserute.length; i++) {

if(i!=reiserute.length)

    z+= avstandArray[reiserute[i]][reiserute[i+1]];

else

    z+= avstandArray[reiserute[i]];

}

Not sure what you are trying to achieve here, although, this is the issue:

your "reiserute" variable has no value in it, it is an empty array and you are trying to access value at different indexes, since there is no data available, javascript will return "undefined".

reiserute[i] ----> undefined

now you are trying to find a value passing reiserute[i], which essentially is undefined.
when you try to access a value of an array using an index, javascript expects your index to be an integer, since your index was evaluated to undefined, it threw NaN error - Nan stands for "NotANumber".

now, you are getting your output as "0" because, length of the array is zero and condition is failing in the first check, hence the loop is not executed.

If your loop executes, you will receive NaN as an error.

This is returning 0 without any issues. As you defined var reiserute = ; the for loop not even running for once.

var avstandArray = [

[0, 62.3, 58.8, 44.6, 33.2],

[62.3, 0, 37.9, 65.3, 60.1],

[58.8, 37.9, 0, 40.5, 78.5],

[44.6, 65.3, 40.5, 0, 77.6],

[33.2, 60.1, 78.5, 77.6, 0]

]



var reiserute = [0,1];



function ruteFunction(){

var z = 0;

for (var i = 0; i < reiserute.length; i++) {

    z+= avstandArray[reiserute[i]][reiserute[i+1]];

    console.log(z);

}

return z;

}



console.log(ruteFunction());