I want to reaturn true/false if there is some duplicates on 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' }
    ]

I found many solutions for one value but what if we want to check the whole object. Do I have to do foreach?

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

CodePudding user response：

you can use JSON.stringify and 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

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CodePudding user response：

Using combo of Array.prototype.some, Array.prototype.every and Object.entries

This checks each item of array against the rest of the array (slice(index 1)) to see if some object is equal.

function hasDuplicates(arr) {
  // check each item of array against rest of the array
  return arr.some((obj, index) => arr.slice(index   1).some(obj2 => {
    // check obj is equal 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