How can I combine each value from an array of objects?

Question

I'm currently doing a simple dice roll app and I have the following object:

die = [
  {
    ofWhat: 6,
    score: [6]
  },
  {
    ofWhat: 6,
    score: [1] 
  },
  {
    ofWhat: 6,
    score: [5] 
  }
]

I would like to get every score and combine them into one value so I can see the total of every score from this array.

Like this: 6+1+5

How can I achieve this?

What I tried:

total = 0;

this.die.forEach((die) => {
  die.score.forEach((score) => {
    this.total += score;
  });
});

I'm getting NaN

Edit: I made an error in my object

die = [
  {
    ofWhat: 6,
    score: [6]
  },
  {
    ofWhat: 6,
    score: [1] 
  },
  {
    ofWhat: 6,
    score: [5] 
  }
]

total = 0;

this.die.forEach((die) => {
  die.score.forEach((score) => {
    this.total += score;
  });
});

console.log(total)

Don't you want a reduce function for this? w3schools.com/jsref/jsref_reduce.asp — Jonathan Smith
– Jonathan Smith, Commented Oct 31, 2019 at 12:50
Shouldn't this this.total += score; not be total += score;? — Rajesh Dixit
– Rajesh Dixit, Commented Oct 31, 2019 at 12:51
How are you getting NaN? die.score.forEach should throw an error — adiga
– adiga, Commented Oct 31, 2019 at 12:51

bhuvnesh pattnaik · Accepted Answer · 2019-10-31 15:23:00Z

2

Try this

        let die = [
          {
            ofWhat: 6,
            score: [6]
          },
          {
            ofWhat: 6,
            score: [1] 
          },
          {
            ofWhat: 6,
            score: [5] 
          }
        ];
        let sum = 0;
        die.forEach(i => {
            i.score.forEach(val => {
                sum += val;
            });
        });
        console.log(sum);

edited Oct 31, 2019 at 15:23

answered Oct 31, 2019 at 12:51

bhuvnesh pattnaik

1,49310 silver badges14 bronze badges

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Comments

Nick Parsons · Accepted Answer · 2019-10-31 13:18:04Z

1

You could use two .reduce() methods, the inner-most reduce() can be used to get the sum of all the elements in your score array, and the outer most reduce() can be used to sum all the results produced by the inner-most reduce():

const die = [{ofWhat:6,score:[6]},{ofWhat:6,score:[1]},{ofWhat:6,score:[5]}];

const total = die.reduce(
    (sum, {score}) => 
      sum+score.reduce((innerSum, n) => innerSum + n, 0), 0);
    
console.log(total);

edited Oct 31, 2019 at 13:18

answered Oct 31, 2019 at 13:09

Nick Parsons

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Comments

David · Accepted Answer · 2019-10-31 12:50:29Z

1

You can use a reducer

die = [
  {
    ofWhat: 6,
    score: 6
  },
  {
    ofWhat: 6,
    score: 1 
  },
  {
    ofWhat: 6,
    score: 5 
  }
]


console.log(die.reduce((acc, curr) => {
  acc += curr.score;
  return acc;
}, 0))

answered Oct 31, 2019 at 12:50

David

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Comments

Mara Black · Accepted Answer · 2019-10-31 12:51:23Z

1

Since you are taking each object from array with this.die.forEach, the content of object can be accessed like a normal object: object.property

die = [
  {
    ofWhat: 6,
    score: 6
  },
  {
    ofWhat: 6,
    score: 1 
  },
  {
    ofWhat: 6,
    score: 5 
  }
]


total = 0;

this.die.forEach((obj) => {
    this.total += obj.score;
});

console.log("total score from die array: " + total)

answered Oct 31, 2019 at 12:51

Mara Black

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1 Comment

Alan S Over a year ago

Sorry, I made an error in my object the score is actually an array of number

Tony · Accepted Answer · 2019-10-31 12:51:41Z

1

var die = [{
    ofWhat: 6,
    score: 6
  },
  {
    ofWhat: 6,
    score: 1
  },
  {
    ofWhat: 6,
    score: 5
  }
];
var sum = 0;
die.forEach(element => {
  sum += element.score;
});

answered Oct 31, 2019 at 12:51

Tony

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Comments

Jacek Rojek · Accepted Answer · 2019-10-31 12:52:01Z

0

die = [
  {
    ofWhat: 6,
    score: 6
  },
  {
    ofWhat: 6,
    score: 1 
  },
  {
    ofWhat: 6,
    score: 5 
  }
]

const total = die.reduce((acc,curr) => acc+curr.score,0)
console.log(total)

answered Oct 31, 2019 at 12:52

Jacek Rojek

1,1328 silver badges16 bronze badges

Comments

Gokul Ramesh · Accepted Answer · 2019-10-31 12:56:43Z

0

You can try this :

this.die.forEach((d) => {
  this.total += d.score;
});

answered Oct 31, 2019 at 12:56

Gokul Ramesh

114 bronze badges

Comments

Hitesh · Accepted Answer · 2019-10-31 12:57:48Z

0

You could iterate over the array using Map

let die = [
    {
      ofWhat: 6,
      score: 6
    },
    {
      ofWhat: 6,
      score: 1 
    },
    {
      ofWhat: 6,
      score: 5 
    }
 ],sum=0;

die.forEach(x=> sum += x.score);
console.log(sum)

edited Oct 31, 2019 at 12:57

answered Oct 31, 2019 at 12:53

Hitesh

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Comments

Erick Lanford Xenes · Accepted Answer · 2019-10-31 13:21:32Z

0

Only use score[0]. 'score' is an array.

  var  die = [
  {
    ofWhat: 6,
    score: [6]
  },
  {
    ofWhat: 6,
    score: [1] 
  },
  {
    ofWhat: 6,
    score: [5] 
  }
];
 

   
total = 0;

this.die.forEach((obj) => {
    this.total += obj.score[0];
});

console.log("total score from die array: " + total)

answered Oct 31, 2019 at 13:21

Erick Lanford Xenes

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Comments

Peter B · Accepted Answer · 2019-10-31 13:45:12Z

You can do this this by adding up all the die.score values.

Updated to use arrays (after the question was updated to use arrays)

If there is always just one array item, you can suffice with adding up each die.score[0] value.
Here we calculate 6+1+5 = 12:

var die = [
  { ofWhat: 6, score: [6] },
  { ofWhat: 6, score: [1] },
  { ofWhat: 6, score: [5] }
]

var total = 0;

this.die.forEach((obj) => {
  total += obj.score[0];
});

console.log(total);

Or if there can be multiple values in each array, you'll need to iterate the inner array as well.
Here we calculate 6+6+1+5 = 18:

var die = [
  { ofWhat: 6, score: [6, 6] },
  { ofWhat: 6, score: [1] },
  { ofWhat: 6, score: [5] }
]

var total = 0;

this.die.forEach((obj) => {
  obj.score.forEach((value) => {
    total += value;
  });
});

console.log(total);

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