CODEWITHSUNDEEP
javascriptreactjs
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hero to zero

Reputation: 31

get only the unique value of an array

I am new to javascript and I tried like using distinct but its not what im looking for

example array:

let arr = [ {key:"1",value:"dog"},
            {key:"1",value:"dog"},
            {key:"2",value:"cat"},
            {key:"3",value:"bird"},
            {key:"3",value:"bird"},
          ]

on the code I try is its just removing the duplicate like 

[ {key:"1",value:"dog"},
  {key:"2",value:"cat"},
  {key:"3",value:"bird"}, ]

how can I get only the 

[ {key:"2",value:"cat"} ]

what I mean is only the one who have no duplicate and its removing those array that have the exact same?

Upvotes: 3

Views: 182

Answers (5)

mssoheil
mssoheil

Reputation: 110

If you don't mind using a library, I strongly suggest using the "ramda" library.

const arr = [ {key:"1",value:"dog"}
          , {key:"1",value:"dog"}
          , {key:"2",value:"cat"}
          , {key:"3",value:"bird"}
          , {key:"3",value:"bird"}
          ];
const result = R.uniq(arr);

result will be: 

[{"key": "1", "value": "dog"}, {"key": "2", "value": "cat"}, {"key": "3", "value": "bird"}]

you can use "lodash" or other similar libraries too.

Upvotes: 0

prabhatojha
prabhatojha

Reputation: 2085

Using the "find" method, you will get exactly what you are looking for "{key:"2",value:"cat"}".

arr.find((item, index) => {
  const foundDup = arr.find((s, sIndex) => sIndex !== index && s.key === item.key);
  return !foundDup;
});

Upvotes: 0

Kannan G
Kannan G

Reputation: 1004

If you can use Javascript libraries such as underscore or lodash, I recommend having a look at _.xorBy function in their libraries. From lodash:

_.xorBy([arrays], [iteratee=_.identity])

Basically, you pass in the array that in here is an object literal and you pass in the attribute that you want to all occurrences of remove duplicates with in the original data array, like this:

var data = [ {key:"1",value:"dog"}
          , {key:"1",value:"dog"}
          , {key:"2",value:"cat"}
          , {key:"3",value:"bird"}
          , {key:"3",value:"bird"}
          ];
var non_duplidated_data = _.xorBy(data, 'key');

Source - https://lodash.com/docs/4.17.14#xorBy

Upvotes: 0

Nick Parsons
Nick Parsons

Reputation: 50749

You can map your objects to stringified versions of your objects so you can then use .indexOf and .lastIndexOf() to compare if the object found appears in different locations in your array, if the last and first index appear in the same location then it can be said that they're the same object (ie: a duplicate doesn't exist) and can be kept in your resulting array like so:

const arr = [{key:"1",value:"dog"},{key:"1",value:"dog"},{key:"2",value:"cat"},{key:"3",value:"bird"},{key:"3",value:"bird"}];

const searchable = arr.map(JSON.stringify);
const res = arr.filter((obj, i) => {
  const str = JSON.stringify(obj);
  return searchable.indexOf(str) === searchable.lastIndexOf(str);
});
console.log(res);

Upvotes: 1

Code Maniac
Code Maniac

Reputation: 37755

You can use reduce and Map

let arr = [{key:"1",value:"dog"},{key:"1",value:"dog"},{key:"2",value:"cat"},{key:"3",value:"bird"},{key:"3",value:"bird"}]

let mapper = arr.reduce( (op,inp) => {
  let {key} = inp
  op.set(key, op.get(key) || {value: inp, count:0})
  op.get(key).count++
  return op
},new Map())


let final = [...mapper.values()].reduce((op,{value,count}) => {
   if(count === 1){
    op.push(value)
   }
   return op
},[])

console.log(final)

Upvotes: 0

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