Combine arrays of objects by comparing two attributes in Typescript

Question

Combine arrays of objects by comparing two attributes in Typescript

Suppose I have an array in TypeScript that looks like this:

const array = [
  { id_m: "123",
    period: "Q1/22",
    amount: 1000
  },
  { id_m: "123",
    period: "Q1/22",
    amount: 500
  },
  { id_m: "123",
    period: "Q2/22",
    amount: 100
  },
]

I aim to condense this array by summing up the amounts based on the properties id_m and period. The desired output should be:

const output = [
  { id_m: "123",
    period: "Q1/22",
    amount: 1500
  },
  { id_m: "123",
    period: "Q2/22",
    amount: 100
  }
]

How can I achieve this most effectively?

typescript aggregate reduce

Answer 1

Answer №1

To begin, input your data. Then, utilize the reduce array method by incrementing the accumulated values with the type you have created. Here's an example:

type Data = {
  id_m: string;
  period: string;
  amount: number;
}

const array: Data[] = [
  { id_m: "123",
    period: "Q1/22",
    amount: 1000
  },
  { id_m: "123",
    period: "Q1/22",
    amount: 500
  },
  { id_m: "123",
    period: "Q2/22",
    amount: 100
  }
];

const result = array.reduce((acc: Data[], info: Data) => {
  const hasItem = acc.find((a) => a.id_m === info.id_m && a.period === info.period);
  if (hasItem) {
    const idx = acc.findIndex((a) => a.id_m === info.id_m && a.period === info.period);
    acc[idx].amount += info.amount;
  } else {
    acc.push(info);
  }

  return acc;
}, []);

console.log(result);

Answer 2

To begin, input your data. Then, utilize the reduce array method by incrementing the accumulated values with the type you have created. Here's an example:

type Data = {
  id_m: string;
  period: string;
  amount: number;
}

const array: Data[] = [
  { id_m: "123",
    period: "Q1/22",
    amount: 1000
  },
  { id_m: "123",
    period: "Q1/22",
    amount: 500
  },
  { id_m: "123",
    period: "Q2/22",
    amount: 100
  }
];

const result = array.reduce((acc: Data[], info: Data) => {
  const hasItem = acc.find((a) => a.id_m === info.id_m && a.period === info.period);
  if (hasItem) {
    const idx = acc.findIndex((a) => a.id_m === info.id_m && a.period === info.period);
    acc[idx].amount += info.amount;
  } else {
    acc.push(info);
  }

  return acc;
}, []);

console.log(result);

Combine arrays of objects by comparing two attributes in Typescript

Answer №1

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