Problem with using for-in/of when returning an object in a function

Question

I just got the result "[object Object]'s score is 0" printed on the terminal. The result 27 was all fine until I separated the function into a return object.

How do I get 27 if I have to return an object?
How do I get "alex" printed on the console.log instead of [object Object]?

const alex = {
  first: [1, 2, 9, 8],
  second: [3],
  third: [0, 0, 0, 1, 3]
};
const gordon = {
  first: [3],
  second: [2, 2, 4, 5, 6, 6, 7, 8]
}

function createPlayer(object) {
  let score = 0;
  return {
    add: function() {
      for (const key in object) {
        for (const item in object[key]) {
          score += object[key][item]
        }
      }
    },
    result: function() {
      return `${object}\'s score is ${score}`
    }
  }
}
createPlayer(alex).add()
console.log(createPlayer(alex).result())

you log createPlayer(alex).result() ... you haven't added anything yet — Jaromanda X
– Jaromanda X, Commented Sep 16, 2020 at 6:24

Jaromanda X · Accepted Answer · 2020-09-16 06:27:33Z

2

const alex = {
  first: [1, 2, 9, 8],
  second: [3],
  third: [0, 0, 0, 1, 3]
};
const gordon = {
  first: [3],
  second: [2, 2, 4, 5, 6, 6, 7, 8]
}

function createPlayer(object, name) {
  let score = 0;
  return {
    add: function() {
      for (const key in object) {
        for (const item in object[key]) {
          score += object[key][item]
        }
      }
      return this; // <<<<<
    },
    result: function() {
      return `${name}\'s score is ${score}`
    }
  }
}
console.log(createPlayer(alex, 'Alex').add().result())

answered Sep 16, 2020 at 6:27

Jaromanda X

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4 Comments

Edith Over a year ago

This is a smart way doing it. Except, I do not understand the meaning of putting"return this" there?

Jaromanda X Over a year ago

so you can chain the methods ... .add() returning this means you can .add().result()

Edith Over a year ago

yes, it does more than chaining the methods. I find that without "return this", even if I .log it separately, the .result method will not show 27. It is like it has no connection with the .add method's result. it is hard to understand for beginner. Do you know what topic I should look into to understand this concept?

Jaromanda X Over a year ago

method chaining? I don't know, been years since I did javascript 101

mplungjan · Accepted Answer · 2020-09-16 06:28:40Z

0

You would not show alex for an object named alex

You might mean this

const alex = {
  Name: "Alex",
  first: [1, 2, 9, 8],
  second: [3],
  third: [0, 0, 0, 1, 3]
};
const gordon = {
  Name: "Gordon",
  first: [3],
  second: [2, 2, 4, 5, 6, 6, 7, 8]
}

function createPlayer(object) {
  let score = 0;
  return {
    add: function() {
      for (const key in object) {
        if (key!=="Name") {
          for (const item in object[key]) {
            score += object[key][item]
          }
        }   
      }
    },
    result: function() {
      return `${object.Name}\'s score is ${score}`
    }
  }
}
const player1 = createPlayer(alex)
player1.add()
console.log(player1.result())

edited Sep 16, 2020 at 6:28

answered Sep 16, 2020 at 6:26

mplungjan

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