CODEWITHSUNDEEP
javascriptarrays
Piyush
Piyush

Reputation: 85

Check if two properties and their respective values are duplicated in array of objects

I have an below array and wanted to return just true or false if we have two property with same value in array of object. As you can see id with 123 have same value as "one". If both are match then return true.

const data = [
  {id: 123, value: "One"},
  {id: 123, value: "One"},
  {id: 143, value: "Two"},
  {id: 153, value: "Three"}
]

Upvotes: 0

Views: 508

Answers (3)

ABGR
ABGR

Reputation: 5205

One approach could be this:

const data = [{id: 123, value: "One"},{id: 123, value: "One"},{id: 143, value: "Two"}, {id: 153, value: "Three"}]

for(let i=0; i< data.length; i++){
 for(let j=i+1; j<data.length; j++){
   if(JSON.stringify(data[i]) === JSON.stringify(data[j])){
     console.log(true);
     break;
   }
 }
}

A better approach with O(N) complexity would be this:

const data = [{id: 123, value: "One"},{id: 123, value: "One"},{id: 143, value: "Two"}, {id: 153, value: "Three"}]

var stringifyElements = data.map(i=> JSON.stringify(i));
console.log(stringifyElements)

var hashMap = {};

for(var i =0; i<stringifyElements.length; i++){
  if(hashMap[stringifyElements[i]] === 1){
    console.log(true);
    break;
  }else{
    hashMap[stringifyElements[i]] = 1
  }
}

Upvotes: 1

Yevhen Horbunkov
Yevhen Horbunkov

Reputation: 15530

You may check whether the size of unique Set of hashes (keys and values concatenated) of all objects within array is less than source array length (which may happen only if there're non-unique key/value combinations):

const dup = [{id: 123, value: "One"},{id: 123, value: "One"},{id: 143, value: "Two"}, {id: 153, value: "Three"}],
      noDup = [{id: 1234, value: "One"},{id: 123, value: "One"},{id: 143, value: "Two"}, {id: 153, value: "Three"}],

      hasDup = arr => 
        new Set(arr.map(({id,value}) => `id|${id}|value|${value}`)).size < arr.length
      
console.log(hasDup(dup))   //true
console.log(hasDup(noDup)) //false

Or, if you need to check for duplicates across all key/value combinations:

const hasDup = arr => 
        new Set(arr.map(o => Object.entries(o).flat().join('|'))).size < arr.length

Upvotes: 2

Siraj Alam
Siraj Alam

Reputation: 10025

Let me know if it needs an explanation.

function doJob(data){
    for(let i = 0; i < data.length; i++){
       let count = data.filter(item => (item.id === data[i].id && item.value === data[i].value)).length;
       if(count > 1) return true
    }
    return false;
}

const data = [
  {id: 123, value: "One"},
  {id: 123, value: "One"},
  {id: 143, value: "Two"},
  {id: 153, value: "Three"}
]

console.log(doJob(data))

Upvotes: 0

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