Using for loop iteration on an array(1st parameter) with an object(second parameter)

Question

const championObj = {1: "Annie", 2: "Olaf", 3: "Galio", 4: "Fizz"}
const championList = ['1','2','1','3','4','3','1']

function countChampions(championObj, championList) {
  //create an empty object to store values
  let obj = {}

  //loop over championList array to compare with championObj object
  for(var i = 0; i < championList.length; i++) {

    //if the index is not in the object, add it into empty object and make the value 1
    if(obj[championObj[championList[i]]] === undefined) {
      obj[championObj[championList[i]]] = 1

    //else if the index is already found in the object, increment the value by + 1 
    } else if (obj[championObj[championList[i]]] !== undefined) {
      obj[championObj[championList[i]]] += 1
    }

    //return the object
    return obj
  }
}

console.log(countChampions(championObj, championList))

When I run this function, I only get { Annie: 1 }

The output should be = {"Annie" : 3, "Olaf" : 1, "Galio": 2, "Fizz": 1}

Premature return

charlietfl
– charlietfl

2020-08-28 00:17:27 +00:00
Commented Aug 28, 2020 at 0:17 — charlietfl
– charlietfl, Commented Aug 28, 2020 at 0:17

Omri Attiya · Accepted Answer · 2020-08-28 00:26:18Z

You get only 1 result because you return obj in the loop, so at the first iteration you end the function. The solution is to return obj after the for block

const championObj = {
  1: "Annie",
  2: "Olaf",
  3: "Galio",
  4: "Fizz"
}
const championList = ['1', '2', '1', '3', '4', '3', '1']

function countChampions(championObj, championList) {
  //create an empty object to store values
  let obj = {}

  //loop over championList array to compare with championObj object
  for (var i = 0; i < championList.length; i++) {

    //if the index is not in the object, add it into empty object and make the value 1
    if (obj[championObj[championList[i]]] === undefined) {
      obj[championObj[championList[i]]] = 1

      //else if the index is already found in the object, increment the value by + 1 
    } else if (obj[championObj[championList[i]]] !== undefined) {
      obj[championObj[championList[i]]] += 1
    }

  }
  //return the object
  return obj
}

console.log(countChampions(championObj, championList))

In addition, since you check your if twice for no reason and use only the values of the array and not the indexes themselves, I want so suggest improvements to your code:

const championObj = {
  1: "Annie",
  2: "Olaf",
  3: "Galio",
  4: "Fizz"
}
const championList = ['1', '2', '1', '3', '4', '3', '1']

function countChampions(championObj, championList) {
  let obj = {}

  for (let value of championList) {
    if (obj[championObj[value]]) {
      obj[championObj[value]]++;
    } else {
      obj[championObj[value]] = 1;
    }
  }

  return obj
}

console.log(countChampions(championObj, championList))

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