Check the duplicate objects in array

Question

I am trying to find the duplicate value in the array of objects and return true value in es6 function.

arrayOne = [{
    agrregatedVal: "count",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "count",
    value: "Pay Date"
  },
  {
    agrregatedVal: "count",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Signature"
  },
  {
    agrregatedVal: "min",
    value: "Pay Date"
  }]

Above is the structure of the json

Here i have two object which are duplicate:

{
  agrregatedVal: "min",
  value: "Employee Full Name"
}, {
  agrregatedVal: "min",
  value: "Employee Full Name"
}

and remaining are not concerned as both values of each object are different.

If each object value is duplicate of another object of same array then it should return true.

I tried in this way:-

this.arrayOne = this.arrayOne.filter((thing, index, self) => {
  return index === self.findIndex((t) => {
    return t.agrregatedVal === thing.agrregatedVal && t.value === thing.value;
  });
});

it dint work, how to return true if object of each value is same of another object.

You never return anything from your callback function. It should be return index === ..., or you should remove the curly braces. — JB Nizet
– JB Nizet, Commented Jul 25, 2019 at 18:46
You must do the same for the inner callback too. jsfiddle.net/twox60dm — JB Nizet
– JB Nizet, Commented Jul 25, 2019 at 18:50
it removes the duplicate value and returns the array but i just need the boolean value instead of array — vinuta
– vinuta, Commented Jul 25, 2019 at 18:52
which boolean value? Explain clearly what your method should do: "my method should return true when...". The code you posted creates a filtered array. — JB Nizet
– JB Nizet, Commented Jul 25, 2019 at 18:57

yanky_cranky · Accepted Answer · 2019-07-25 19:25:02Z

1

Here are few things :

1) Has Duplicates :

it dint work, how to return true if object of each value is same of another object.

const dict=arrayOne.map((item,pos)=>{
  return item.agrregatedVal+":"+item.value;
});


hasDuplicate=dict.some(function(item, id){ 
     if(dict.indexOf(item) != id)
       return item;
});

console.log(hasDuplicate);

2) Remove Duplicates :

 unique = [...new Set(arrayOne.map(a => a.agrregatedVal+ "':'"+ a.value))];

Now, you can construct back your object with these

answered Jul 25, 2019 at 19:25

yanky_cranky

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Comments

Bill Cheng · Accepted Answer · 2019-07-25 19:43:35Z

Try this:

const arrayOne = [{
    agrregatedVal: "count",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "count",
    value: "Pay Date"
  },
  {
    agrregatedVal: "count",
    value: "Employee Full Name"
  },
  {
    agrregatedVal: "min",
    value: "Signature"
  },
  {
    agrregatedVal: "min",
    value: "Pay Date"
  }]

function hasDuplicate(arrayOne) {
  const newArray = arrayOne.filter((thing, index, self) => index === self.findIndex(t => t.agrregatedVal === thing.agrregatedVal && t.value === thing.value));

  return newArray.length < arrayOne.length;
}

console.log(hasDuplicate(arrayOne));

hasDupliecate will return true if there is/are duplicates

Alex Lomia · Accepted Answer · 2019-07-25 20:20:37Z

De-duplicating an array

Consider the following implementation:

const initialArray = [
  {agrregatedVal: "count", value: "Employee Full Name"},
  {agrregatedVal: "min", value: "Employee Full Name"},
  {agrregatedVal: "min", value: "Employee Full Name"},
];

const dedupedArray = [
  ...new Set(initialArray.map(item => JSON.stringify(item)))
].map(itemJson => JSON.parse(itemJson));

console.log(dedupedArray);

Every item in the original array is converted to Json string
The strings are dumped inside a Set which discards the duplicates
The Set, which now contains only unique Json strings, is converted back into an array
The objects are recreated back from the strings

A function which determines if an object is duplicated inside an array

I think what you actually want to achieve is to have a function that determines if an object is a duplicate of another object in an array, right?

const array = [
  {agrregatedVal: "count", value: "Employee Full Name"},
  {agrregatedVal: "min", value: "Employee Full Name"},
  {agrregatedVal: "min", value: "Employee Full Name"},
];

const isDuplicate = (itemA, array) => !!array.find(itemB => itemA !== itemB && JSON.stringify(itemA) === JSON.stringify(itemB));

console.log(isDuplicate(array[1], array))

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