Question 401751 in Javascript Question posted in
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Javascript – Sum values of object with coefficients of another object

I want to sum costs with coefficients in done object like this:


const costs = {a: 2000, b: 5000, c: 4000}

const done = {a: 1, b: 1, c: 2}

(1 * 2000) + (1 * 5000) + (2 * 4000) = 15000

I tried this with no luck:

function sumObjectsByKey(...objs) {
  return objs.reduce((a, b) => {
    for (let k in b) {
      if (b.hasOwnProperty(k))
        a[k] += (a[k] || 0) * b[k];
    }
    return a;
  }, {});
}

console.log(sumObjectsByKey(obj1, obj2, obj3));

Any suggestions?

Tags:

4

Answers


  1. 0 
    const costs = {a: 2000, b: 5000, c: 4000};
const done = {a: 1, b: 1, c: 2};

let total = 0;

for (let key in done) {
    total += done[key] * costs[key];
}

console.log(total); // Output: 15000

or

const costs = {a: 2000, b: 5000, c: 4000};
const done = {a: 1, b: 1, c: 2};

const total = Object.keys(done).reduce((sum, key) => {
    return sum + (done[key] * costs[key]);
}, 0);

console.log(total); // Output: 15000
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  2. 0

    const costs = {a: 2000, b: 5000, c: 4000};
    const done = {a: 1, b: 1, c: 2};

    const total = Object.keys(done).reduce((sum, key) => sum + (costs[key] || 0) * done[key], 0);

    console.log(total); // 15000

    It will give you the answer with costs and done

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  3. 0

    You can use nested Array#reduce operations for this task.

    const costs = {a: 2000, b: 5000, c: 4000},
      done = {a: 1, b: 1, c: 2};

const sumObjectsByKey = (...objs) => Object.keys(objs[0] ?? {})
  .reduce((tot, k) => tot + objs.reduce((a, o) => a * o[k], 1), 0);

// assuming first object has all the keys

console.log(sumObjectsByKey(costs, done));
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  4. 0

    I guess it’s not the fastest way, but here’s another approach.

    const sumObjectsByKey = (...objects) => {
  const transformed = {};
  objects.forEach((obj) => {
    for (const key in obj) {
      transformed[key]?.length
        ? transformed[key].push(obj[key])
        : (transformed[key] = [obj[key]]);
    }
  });

  let result = 0;

  for (const key in transformed) {
    result += transformed[key].reduce(
      (acc, next) => (acc ? acc * next : next),
      0,
    );
  }

  return result;
};
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