Get an array of strings from an array of objects with conditions

Question

What is the best way to get an array of strings from an array of objects, where you can specify to only take value x where value y=z?

Current solution:

    array = [{
        "Item": "A",
        "Quantity": 2
      },
      {
        "Item": "B",
        "Quantity": 7
      },
      {
        "Item": "C",
        "Quantity": 7
      },
      {
        "Item": "D",
        "Quantity": 7
      },
      {
        "Item": "E",
        "Quantity": 7
      },
      {
        "Item": "F",
        "Quantity": 1
      }
    ];
    
    let filteredValues = array.map((el) => el.Quantity === 7 && el.Item);
    
    console.log(filteredValues)

Expected outcome:

["B", "C", "D", "E"]

Actual outcome:

[false, "B", "C", "D", "E", false]

Additional info: using next.js / react

Amila Senadheera · Accepted Answer · 2022-03-06 03:33:22Z

3

First, do filter and then do a map to get only the property you need.

const array = [
  { Item: "A", Quantity: 2 },
  { Item: "B", Quantity: 7 },
  { Item: "C", Quantity: 7 },
  { Item: "D", Quantity: 7 },
  { Item: "E", Quantity: 7 },
  { Item: "F", Quantity: 1 },
];

let filteredValues = array
  .filter((el) => el.Quantity === 7 && el.Item)
  .map(({ Item }) => Item);

console.log(filteredValues);

Or, you can use reduce as below.

const array = [
  { Item: "A", Quantity: 2 },
  { Item: "B", Quantity: 7 },
  { Item: "C", Quantity: 7 },
  { Item: "D", Quantity: 7 },
  { Item: "E", Quantity: 7 },
  { Item: "F", Quantity: 1 },
];

let filteredValues = array.reduce((results, el) => {
  if (el.Quantity === 7 && el.Item) {
    results.push(el.Item);
  }
  return results;
}, []);

console.log(filteredValues);

edited Mar 6, 2022 at 3:33

answered Mar 6, 2022 at 3:14

Amila Senadheera

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1 Comment

Amila Senadheera Over a year ago

@user1898662, check this out !!

Rohìt Jíndal · Accepted Answer · 2022-03-06 13:53:23Z

1

Use Array.filter() along with Array.map()

Working Demo :

const array = [{
  "Item": "A",
  "Quantity": 2
},             {
  "Item": "B",
  "Quantity": 7
},             {
  "Item": "C",
  "Quantity": 7
},{
  "Item": "D",
  "Quantity": 7
},{
  "Item": "E",
  "Quantity": 7
},{
  "Item": "F",
  "Quantity": 1
}];

const filteredValues = array.filter((el) => el.Quantity === 7).map(elem => elem.Item);
    
console.log(filteredValues)

answered Mar 6, 2022 at 13:53

Rohìt Jíndal

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2 Comments

user1898662 Over a year ago

Thanks, this worked. Is there a way to make the return list one with no duplicate values?

Rohìt Jíndal Over a year ago

Yes you can achieve that by using [...new Set(filteredValues)]

Yves Kipondo · Accepted Answer · 2022-03-06 03:19:38Z

1

The best way is to use Array.prototype.reduce

let data = [{
    "Item": "A",
    "Quantity": 2
  },
  {
    "Item": "B",
    "Quantity": 7
  },
  {
    "Item": "C",
    "Quantity": 7
  },
  {
    "Item": "D",
    "Quantity": 7
  },
  {
    "Item": "E",
    "Quantity": 7
  },
  {
    "Item": "F",
    "Quantity": 1
  }
];

const result = data.reduce((accumulator, current) => {
  return current["Quantity"] === 7 ? accumulator.concat(current["Item"]): accumulator;
}, [])

console.log(result);

answered Mar 6, 2022 at 3:19

Yves Kipondo

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