sum of specific key for multiple similar keys in array of object - JavaScript

Question

I have an array of objects like the following:

[
    {
        'Product': 'P1',
        'Price': 150,
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 100,
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 200,
        'Location': 2,
    },
    {
        'Product': 'P2',
        'Price': 10,
        'Location': 1,
    },
    {
        'Product': 'P2',
        'Price': 130,
        'Location': 1,
    },
    {
        'Product': 'P3',
        'Price': 40,
        'Location': 1,
    }
]

I need to add up all the prices for objects with the same product and same location. For the example above the result would be:

[
   {
        'Product': 'P1',
        'Price': 250, // price is the sum of both similar in location and product
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 200,
        'Location': 2, // same product but different location
    },
    {
        'Product': 'P2',
        'Price': 140, //sum of same
        'Location': 1, 
    },
    {
        'Product': 'P3',
        'Price': 40,
        'Location': 1,
    },
]

I have searched several similar issues, but those were dealing with only one key to check for, I have different keys (product and location - may be more than 2 in the future) to identify as different.

topdev87 · Accepted Answer · 2021-01-11 07:16:03Z

const input = [
    {
        'Product': 'P1',
        'Price': 150,
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 100,
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 200,
        'Location': 2,
    },
    {
        'Product': 'P2',
        'Price': 10,
        'Location': 1,
    },
    {
        'Product': 'P2',
        'Price': 130,
        'Location': 1,
    },
    {
        'Product': 'P3',
        'Price': 40,
        'Location': 1,
    }
]

const output = []
input.forEach(item => {
  const index = output.findIndex(o => o.Product === item.Product && o.Location === item.Location);
  if (index === -1) {
    output.push(item);
  } else {
    output[index].Price += item.Price;
  }
});
console.log(output);

Without arrow function

input.forEach(function(item) {
  const index = output.findIndex(function(o) { return o.Product === item.Product && o.Location === item.Location});
  if (index === -1) {
    output.push(item);
  } else {
    output[index].Price += item.Price;
  }
});

Md Sabbir Alam · Accepted Answer · 2021-01-08 07:45:05Z

You can use reduce() to do that,

obj = [
   {
        'Product': 'P1',
        'Price': 250, // price is the sum of both similar in location and product
        'Location': 1,
    },
    {
        'Product': 'P1',
        'Price': 200,
        'Location': 2, // same product but different location
    },
    {
        'Product': 'P2',
        'Price': 140, //sum of same
        'Location': 1, 
    },
    {
        'Product': 'P3',
        'Price': 40,
        'Location': 1,
    },
]

res = obj.reduce((prev, curr) => {
  index = prev.findIndex(item => item.Product=== curr.Product && item.Location === curr.Location);
  if(index > -1) {
    prev[index].Price += curr.Price;
  } else {
    prev.push(curr);
  }
  return prev;
}, []);

console.log(res);

Tibebes. M · Accepted Answer · 2021-01-12 18:17:48Z

0

Modifying @William's answer (Accepted) for my use case as it was to be run on the platform which was not supporting ES6 features (findIndex and arrow function), this can be done without findIndex as below;

var input = [{
    'Product': 'P1',
    'Price': 150,
    'Location': 1,
  },
  {
    'Product': 'P1',
    'Price': 100,
    'Location': 1,
  },
  {
    'Product': 'P1',
    'Price': 200,
    'Location': 2,
  },
  {
    'Product': 'P2',
    'Price': 10,
    'Location': 1,
  },
  {
    'Product': 'P2',
    'Price': 130,
    'Location': 1,
  },
  {
    'Product': 'P3',
    'Price': 40,
    'Location': 1,
  }
]

var output = []
input.forEach(function(item) {
  var index = output.indexOf(output.filter(function(o) {
    return o.Product === item.Product && o.Location === item.Location
  })[0]); // note the [0] index here
  if (index === -1) {
    output.push(item);
  } else {
    output[index].Price += item.Price;
  }
});
console.log(output);

edited Jan 12, 2021 at 18:17

Tibebes. M

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answered Jan 12, 2021 at 18:10

Mangrio

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1 Comment

Tibebes. M Over a year ago

there is a button that reads "Tidy" inside the snippet editor that formats your code - please use that after you finish editing your snippet. (it's right below "save and insert post" button)

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