I have created an Array with some numbers. I want to find out how many even, and how many odd numbers it is in this Array. I have to print it out like this: (this is just an example)

Even number: 6

Odd number: 7

I need to make a loop that count up how many it is off even and odd numbers.

This is what I have so far

<script>

window.onload = run;

  var tall = [5,10,15,20,25,30,35,40,45,50];

  function run() {

    tall = [5,10,15,20,25,30,35,40,45,50];

    liste(tall);

  }

  function liste(arr) {

    var sumOdd = 0; // Odd 1, 3, 5 etc..
    var sumPar = 0; // Even 2, 4, 6 etc..

    for(var i = 0; i < arr.length; i++) {
      if(arr[i] % 2 === 0) {
        sumPar += arr.length;
    }
      else {
        sumOdd += arr.length;
      }                                            // Even numbers                     // Odd numbers
      document.getElementById("print").innerHTML = "Partall:  " + sumPar + "<br />" + "Oddetall:  " + sumOdd;

  }

  }
}
</script>

Its something that is wrong here, and I dont know what.

I have created an Array with some numbers. I want to find out how many even, and how many odd numbers it is in this Array. I have to print it out like this: (this is just an example)

Even number: 6

Odd number: 7

I need to make a loop that count up how many it is off even and odd numbers.

This is what I have so far

<script>

window.onload = run;

  var tall = [5,10,15,20,25,30,35,40,45,50];

  function run() {

    tall = [5,10,15,20,25,30,35,40,45,50];

    liste(tall);

  }

  function liste(arr) {

    var sumOdd = 0; // Odd 1, 3, 5 etc..
    var sumPar = 0; // Even 2, 4, 6 etc..

    for(var i = 0; i < arr.length; i++) {
      if(arr[i] % 2 === 0) {
        sumPar += arr.length;
    }
      else {
        sumOdd += arr.length;
      }                                            // Even numbers                     // Odd numbers
      document.getElementById("print").innerHTML = "Partall:  " + sumPar + "<br />" + "Oddetall:  " + sumOdd;

  }

  }
}
</script>

Its something that is wrong here, and I dont know what.

• javascript

Share Improve this question Follow edited Oct 28, 2016 at 9:44 Mistalis 18.3k1414 gold badges7777 silver badges9797 bronze badges asked Oct 28, 2016 at 9:30 celllaa95celllaa95 3511 silver badge99 bronze badges 4

• += arr.length makes no sense. You just want += 1, or ++. – deceze ♦ Commented Oct 28, 2016 at 9:32
• Why are you adding the length of the array each time? If you want to count the number of elements that are odd or even, add one each time, if you want to add the value itself each time then do arr[i]. – DibsyJr Commented Oct 28, 2016 at 9:33
• Don't you add the length of tall (so 10) every time you find a number? You would just need to add 1 every time you find one, not the length of the array. – Lehue Commented Oct 28, 2016 at 9:33
• I have been trying differents things. I started to try the arr[i], but the result was that they were summed together, and thats not what I wanted – celllaa95 Commented Oct 28, 2016 at 9:36

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3 Answers 3

Sorted by: Reset to default 5

You could iterate with Array#reduce and count only the odds. For the rest just take the difference of the length of the array and the odds.

var tall = [5, 10, 15, 20, 25, 30, 35, 40, 45, 50],
    odd = tall.reduce(function (r, a) { return r + a % 2; }, 0),
    even = tall.length - odd;

console.log('odd', odd);
console.log('even', even);

You were adding arr.length which is the array length. Instead you should simply increment the number

var tall = [5, 10, 15, 20, 25, 30, 35, 40, 45, 50];

liste(tall);

function liste(arr) {
  var sumOdd = 0;
  var sumPar = 0;

  for (var i = 0; i < arr.length; i++) {
    if (arr[i] % 2 === 0) {
      sumPar++;
    } else {
      sumOdd++;
    }
  }
  
  console.log("Odd : " + sumOdd);
  console.log("Par : " + sumPar);
}

You always add the plete Length of the array to your variable

Try this instead of sumPar += arr.length;:

sumPar++;