Question 54592 in Javascript Question posted in
A very good W3school tutorial can be found here.

Creating separate arrays for even and odd numbers – Javascript

This is beginner level. I am trying to create separate arrays for odd and even numbers from the parent array. Below the code:


const arr = [22, 33, 44, 55, 66]
let even = []
let odd = []



function separateArray(arr) {

    let j, k

    for( let i = 0; i < arr.length; i++ ) {

        if( arr[i]%2 === 0 ){

            even[j] = arr[i]
            j++

        }else {

            odd[k] = arr[i]
            k++

        }
        
    }   
}

separateArray(arr)

for( let i = 0; i < even.length; i++ ) {

    console.log(even[i])

}

I tried calling the function separateArray and then log the even numbers in the console. But it doesn’t display anything.

Tags:

2

Answers


  1. 0

    The reason why you are not seeing anything in the console is because you have not initialized the values of j and k.
    In JavaScript, accessing an undefined variable will result in a ReferenceError. You need to initialize j and k to 0 before using them as array indices:

    const arr = [22, 33, 44, 55, 66];
let even = [];
let odd = [];

function separateArray(arr) {
  let j = 0,
    k = 0;
  for (let i = 0; i < arr.length; i++) {
    if (arr[i] % 2 === 0) {
      even[j] = arr[i];
      j++;
    } else {
      odd[k] = arr[i];
      k++;
    }
  }
}

separateArray(arr);

for (let i = 0; i < even.length; i++) {
  console.log(even[i]);
}
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  2. 0

    Just for fun, here is what you will be able to do one day when you get into more advanced javascript…

    const arr = [22, 33, 44, 55, 66]

const [even, odd] = arr.reduce((a,c)=>(a[c%2].push(c),a),[[],[]])

console.log(odd)
console.log(even)
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