Remove one of two duplicated fields in object array javascript/react-native

Question

i have an array of objects that returns name: string and quantity: number, the thing is i have many objects into the array with the same name field value but different quantity values, so i want to show the total of all the quantities for each duplicated name. My code here:

const productsArray = [{ name: "lamp", quantity: 10 }, {name: "glass", quantity: 4}, {name:"lamp", quantity: 5}]

Lamp is repeated but it has different quantity values, so i want to merge those quantity values into one total quantity and show the name only once.

DESIRED RESULT

PRODUCT NAME: lamp PRODUCT QUANTITY: 15

PRODUCT NAME: glass PRODUCT QUANTITY: 4

Please help

Shing Ho Tan · Accepted Answer · 2019-12-09 02:50:16Z

1

Here is one option:-

const productsArray = [{ name: "lamp", quantity: 10 }, {name: "glass", quantity: 4}, {name:"lamp", quantity: 5}]


var output = [];

productsArray.forEach(function(item) {
  var existing = output.filter(function(v, i) {
    return v.name == item.name;
  });
  if (existing.length) {
    var existingIndex = output.indexOf(existing[0]);
    output[existingIndex].quantity += item.quantity;
  } else {
    output.push(item);
  }
});

console.dir(output);

answered Dec 9, 2019 at 2:50

Shing Ho Tan

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Comments

Nick · Accepted Answer · 2019-12-09 02:53:49Z

0

I'd probably use a combination of reduce, Object.entries, and map to accomplish this.

const productsArray = [{ name: "lamp", quantity: 10 }, {name: "glass", quantity: 4}, {name:"lamp", quantity: 5}];

const combined = productsArray.reduce((acc, el) => {
  if (acc[el.name] === undefined) {
    acc[el.name] = 0;
  }
  acc[el.name] += el.quantity;
  return acc;
}, {});

const final = Object.entries(combined).map(([name, quantity]) => ({
  name,
  quantity
}));

console.log(final);

answered Dec 9, 2019 at 2:53

Nick

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Comments

Carlos Moreira · Accepted Answer · 2019-12-09 02:49:08Z

0

You mean something like this?

let productsObj = {};
for (let i = 0; i < productsArray.length; i++) {
  let item = productsArray[i];
  if (!!(productsObj[item.name])) {
    productsObj[item.name] += item.quantity;
  } else {
    productsObj[item.name] = item.quantity;
  }
}

This way you can basically use an object as a key-value pair of items and access them using the name of the product (or its id, if you have it). To revert it back to a list you can do this:

const productsArray = [];
for (let name in productsObj) {
   productsArray.push({ name: name, quantity: productsObj[name] });
}

answered Dec 9, 2019 at 2:49

Carlos Moreira

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Comments

albert · Accepted Answer · 2019-12-09 03:11:07Z

0

Alternative would be doing something like below: https://jsfiddle.net/yo2sad95/

const productsArray = [
  { name: 'lamp', quantity: 10 },
  { name: 'glass', quantity: 4 },
  { name: 'lamp', quantity: 5 },
]

const quantities = productsArray.reduce((accum, curr) => {
  const value = accum[curr.name] || 0
  return { ...accum, [curr.name]: value + curr.quantity }
}, {})

const result = Object.keys(quantities).map(product => ({ [product]: quantities[product] }))
console.warn(result)

answered Dec 9, 2019 at 3:11

albert

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