How to find matching items in array of objects with ES6

Question

How can I find items which have same name prop in the following array of objects with with ES6?

var pilots = [
  {
    id: 2,
    name: "Wedge Antilles",
    faction: "Rebels",
  },
  {
    id: 8,
    name: "Ciena Ree",
    faction: "Empire",
  },
  {
    id: 8,
    name: "Ciena Ree",
    faction: "Empire",
  },
  {
    id: 40,
    name: "Iden Versio",
    faction: "Empire",
  },
  {
    id: 66,
    name: "Thane Kyrell",
    faction: "Rebels",
  }
];

var rebels = pilots.filter(function (item) {
  return item.name === item.name;
});


console.log(rebels)

I tried this solution but it didn't work, it's returned all items.

It returns all items because you're checking it against itself. Are you wanting to return all duplicates or just return ones that match a specific case? I.e. all that match name 'Ciena Ree'? — Liam MacDonald
– Liam MacDonald, Commented Sep 11, 2019 at 12:40
Your condition is always true, that's why it returns all the items. You need to change it by that, for example: return item.name === "Thane Kyrell"; — ThibaultV
– ThibaultV, Commented Sep 11, 2019 at 12:40
return item.name === item.name; <-- does the item's name matches the item name.... I hope it does — epascarello
– epascarello, Commented Sep 11, 2019 at 12:40
item.name === item.name ? comparing the value with itself will always return true you will get all the values in output — Code Maniac
– Code Maniac, Commented Sep 11, 2019 at 12:40

Kasia · Accepted Answer · 2019-09-11 13:08:35Z

3

the beauty of reduce - this method will eliminate the same objects

const tada = data.reduce((result, currentItem) =>
 result.includes(currentItem) ? result : [...result, currentItem], [])

we can specify what type of duplication we want to avoid (by property name)

const tada = data.reduce((result, currentItem) =>
 result.some(el => el.name === currentItem.name) ? result : [...result, currentItem], [])

if you want to find duplications (by name)

const tada = data.reduce(
  (result, currentItem, index) =>
    data.some(
      (el, innerIndex) => el.name === currentItem.name && index !== innerIndex
    )
      ? [...result, currentItem]
      : result,
  []
);

edited Sep 11, 2019 at 13:08

answered Sep 11, 2019 at 12:50

Kasia

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Comments

Karan · Accepted Answer · 2019-09-11 12:53:59Z

2

The following code will return elements whose name appears in more than one element

var pilots = [
  {
    id: 2,
    name: "Wedge Antilles",
    faction: "Rebels",
  },
  {
    id: 8,
    name: "Ciena Ree",
    faction: "Empire",
  },
  {
    id: 8,
    name: "Ciena Ree",
    faction: "Empire",
  },
  {
    id: 40,
    name: "Iden Versio",
    faction: "Empire",
  },
  {
    id: 66,
    name: "Thane Kyrell",
    faction: "Rebels",
  }
];

var rebels = pilots.filter(function (item, idx) {
  return pilots.some((v, i) => v.name === item.name && idx != i)
});

console.log(rebels)

edited Sep 11, 2019 at 12:53

Karan

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answered Sep 11, 2019 at 12:44

Avraham

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Comments

ankit singh · Accepted Answer · 2019-09-11 12:58:55Z

Please use this code it will return which name are repeating in the pilots object

    <script type="text/javascript">
        var pilots = [
      {
        id: 2,
        name: "Wedge Antilles",
        faction: "Rebels",
      },
      {
        id: 8,
        name: "Ciena Ree",
        faction: "Empire",
      },
      {
        id: 8,
        name: "Ciena Ree",
        faction: "Empire",
      },
      {
        id: 40,
        name: "Iden Versio",
        faction: "Empire",
      },
      {
        id: 66,
        name: "Thane Kyrell",
        faction: "Rebels",
      }
    ];
    var obj = {};
    var rebels = pilots.filter(function (item) {
        if(!obj[item.name]) {
         obj[item.name] = item.name;
        } else {
            return item.name == item.name;
        }
    });
    console.log(rebels)
    </script>

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