Determine whether or not there are any duplicate elements within an array object

Question

Determine whether or not there are any duplicate elements within an array object

Is there a way to determine true or false if there are any duplicates within an object array?

arr = [
     { nr:10, name: 'aba' },
     { nr:11, name: 'cba' },
     { nr:10, name: 'aba' }
]

 arr2 = [
         { year:2020, city: 'Aaa' },
         { year:2010, city: 'Bbb' },
         { year:2020, city: 'Aaa' }
    ]

While there are numerous solutions available for checking duplicate values, what if we need to check the entire object? Would using a foreach loop be necessary?

 const result: T[] = [];
    for (const item of array) {
        if (!result.includes(item)) {
            result.push(item);
        }
    }
    return result;

angular typescript arrayobject

Answer 1

Answer №1

To check for duplicates in an array, you can utilize JSON.stringify along with the map and some array methods.

let arr = [
     { nr:10, name: 'aba' },
     { nr:11, name: 'cba' },
     { nr:10, name: 'aba' }

]


 let valuesStringify = arr2.map(x => JSON.stringify(x));

 let duplicate = valuesStringify.some((item, i) => valuesStringify.indexOf(item) !== i)

console.log(duplicate) //true

Click here for the example

Answer 2

To check for duplicates in an array, you can utilize JSON.stringify along with the map and some array methods.

let arr = [
     { nr:10, name: 'aba' },
     { nr:11, name: 'cba' },
     { nr:10, name: 'aba' }

]


 let valuesStringify = arr2.map(x => JSON.stringify(x));

 let duplicate = valuesStringify.some((item, i) => valuesStringify.indexOf(item) !== i)

console.log(duplicate) //true

Click here for the example

Answer 3

Answer №2

Utilizing a combination of Array.prototype.some, Array.prototype.every, and Object.entries

This method iterates through each item in the array compared to the remaining items in the array (slice(index + 1)) to determine if any objects are identical.

function hasDuplicates(arr) {
  // compare each item in the array with the rest of the array
  return arr.some((obj, index) => arr.slice(index + 1).some(obj2 => {
    // check if obj is equal to obj2
    return Object.entries(obj).every(([key, value]) => obj2[key] === value)
  }))
}

let arr = [
  { nr:10, name: 'aba' },
  { nr:11, name: 'cba' },
  { nr:10, name: 'aba' }
];

let arr2 = [
  { year:2020, city: 'Aaa' },
  { year:2010, city: 'Bbb' },
  { year:2020, city: 'Ccc' }
];

console.log(hasDuplicates(arr)); // true
console.log(hasDuplicates(arr2)); // false

Answer 4

Utilizing a combination of Array.prototype.some, Array.prototype.every, and Object.entries

This method iterates through each item in the array compared to the remaining items in the array (slice(index + 1)) to determine if any objects are identical.

function hasDuplicates(arr) {
  // compare each item in the array with the rest of the array
  return arr.some((obj, index) => arr.slice(index + 1).some(obj2 => {
    // check if obj is equal to obj2
    return Object.entries(obj).every(([key, value]) => obj2[key] === value)
  }))
}

let arr = [
  { nr:10, name: 'aba' },
  { nr:11, name: 'cba' },
  { nr:10, name: 'aba' }
];

let arr2 = [
  { year:2020, city: 'Aaa' },
  { year:2010, city: 'Bbb' },
  { year:2020, city: 'Ccc' }
];

console.log(hasDuplicates(arr)); // true
console.log(hasDuplicates(arr2)); // false

Determine whether or not there are any duplicate elements within an array object

Answer №1

Answer №2

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