JavaScript Reduce with Objects

Question

This is my object

   let products = [
      { "productName": "A", "storage": "Lot 1", "quantity": 1000, "status": "stockIn" },
      { "productName": "A", "storage": "Lot 1", "quantity": 100, "status": "stockIn"  },
      { "productName": "A", "storage": "Lot 1", "quantity": 500, "status": "stockOut" },
      { "productName": "A", "storage": "Lot 2", "quantity": 500, "status": "stockIn"  }
   ]

This is what I am trying to achieve

   let result = [
      { "productName": "A", "storage": "Lot 1", "stockIn": 1100, "stockOut": 500, "available":600 },
      { "productName": "A", "storage": "Lot 2", "stockIn": 500, "stockOut": 0, "available":500   }
   ]

Please kindly provide an idea on how to achieve this without redundant codes. Thanks

var storage = new Set(products.map(item => item.storage));

storage.forEach(lot => {

var stockIn = products.filter(item => item.storage === storage && item.status == 'stockIn')
    .map(({ storage, quantity }) => ({ storage, quantity }));

var stockInSum = stockIn.reduce((prev, curr, index) => prev + curr.quantity, 0);

var stockOut = products.filter(item => item.storage === storage && item.status == 'stockOut')
    .map(({ storage, quantity }) => ({ storage, quantity }))

var stockOutSum = stockOut.reduce((prev, curr, index) => prev + curr.quantity, 0);

}

What have you tried so far to solve this on your own?

Andreas
– Andreas

2022-02-26 12:43:57 +00:00
Commented Feb 26, 2022 at 12:43 — Andreas
– Andreas, Commented Feb 26, 2022 at 12:43
@Andreas I have updated my code. I tried that.

Honey Singh
– Honey Singh

2022-02-26 12:55:06 +00:00
Commented Feb 26, 2022 at 12:55 — Honey Singh
– Honey Singh, Commented Feb 26, 2022 at 12:55

Majed Badawi · Accepted Answer · 2022-02-26 12:53:59Z

1

Using Array#reduce, iterate over the array while updating a Map where the key is the combination of productName and storage, and the value is the corresponding grouped object
In every iteration, using the current key, get the pair if exist and deconstruct stockIn and stockOut. According to the current status, update one of the latter values and compute available. Finally, using Map#set, create/update the pair.
Using Map#values, get the list of grouped objects

const products = [
  { productName: "A", storage: "Lot 1", quantity: 1000, status: "stockIn" },
  { productName: "A", storage: "Lot 1", quantity: 100,  status: "stockIn"  },
  { productName: "A", storage: "Lot 1", quantity: 500,  status: "stockOut" },
  { productName: "A", storage: "Lot 2", quantity: 500,  status: "stockIn"  }
];

const result = [...
  products.reduce((map, { productName, storage, quantity, status }) => {
    const key = `${productName}-${storage}`;
    let { stockIn = 0, stockOut = 0 } = map.get(key) ?? {};
    if(status === 'stockIn') stockIn += quantity;
    else stockOut += quantity;
    const available = stockIn - stockOut;
    map.set(key, { productName, storage, stockIn, stockOut, available });
    return map;
  }, new Map)
  .values()
];

console.log(result);

answered Feb 26, 2022 at 12:53

Majed Badawi

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1 Comment

Honey Singh Over a year ago

Brilliant. Works like a charm. You are the man. .Thanks bro.

Steven Spungin · Accepted Answer · 2022-02-26 12:46:29Z

0

Here is the general pattern. I will leave it to you to figure out the other fields.

const reduced = products.reduce( (a,v) => {
  const found = a.find(it=>it.lot === v.lot && it.productName === v.productName)
  if (found) {
    a.quantity += v.quantity
    // aggregate your other fields here.
  }
  else {
    a.push(v)
  }
  return a
}, [] )

answered Feb 26, 2022 at 12:46

Steven Spungin

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