Checking for duplicates in a TypeScript array of objects

Question

Checking for duplicates in a TypeScript array of objects

I am facing a requirement where I must check for duplicates among object items.

Within the following Array of objects, I need to specifically look for duplicates in either the "empno" or "extension" properties. If any duplicates are found, an error should be triggered.

I attempted using this Stack Overflow link as a reference, but unfortunately, it did not provide the solution I needed.

[
    {
        "id": 269,
        "empno": "34567",
        "extension": 345
    },
    {
        "id": 269,
        "empno": "34568",
        "extension": 346
    },
    {
        "id": 269,
        "empno": "34569",
        "extension": 345
    },
    {
        "id": 269,
        "empno": "34567",
        "extension": 345
    }
]

javascript angularjs angular typescript

Answer 1

Answer №1

To efficiently check for duplicates in a dataset, one approach is to use a Set to store unique combinations of values:

const hasDuplicates = (data) => {
  const set = new Set();

  for (let {empno, extension} of data) {
    const key = `${empno}/${extension}`;
    if (set.has(key)) {
      return true;
    }

    set.add(key);
  }

  return false;
};

Complete code snippet:

const data = [{
    "id": 269,
    "empno": "34567",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34568",
    "extension": 346
  },
  {
    "id": 269,
    "empno": "34569",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34567",
    "extension": 345
  }
];

const hasDuplicates = (data) => {
  const set = new Set();
  
  for (let {empno, extension} of data) {
    const key = `${empno}/${extension}`;
    if (set.has(key)) {
      return true;
    }
    
    set.add(key);
  }
  
  return false;
};

console.log(hasDuplicates(data));

For a more concise solution that checks for duplicates by comparing the size of the array with a Set, you can use the following code snippet:

const hasDuplicates = (data) => data.length !== data.reduce((a, {empno, extension}) => a.add(`${empno}/${extension}`), new Set).size;

Complete code snippet:

const data = [{
    "id": 269,
    "empno": "34567",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34568",
    "extension": 346
  },
  {
    "id": 269,
    "empno": "34569",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34567",
    "extension": 345
  }
];

const hasDuplicates = (data) => data.length !== data.reduce((a, {empno, extension}) => a.add(`${empno}/${extension}`), new Set).size;

console.log(hasDuplicates(data));

Answer 2

To efficiently check for duplicates in a dataset, one approach is to use a Set to store unique combinations of values:

const hasDuplicates = (data) => {
  const set = new Set();

  for (let {empno, extension} of data) {
    const key = `${empno}/${extension}`;
    if (set.has(key)) {
      return true;
    }

    set.add(key);
  }

  return false;
};

Complete code snippet:

const data = [{
    "id": 269,
    "empno": "34567",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34568",
    "extension": 346
  },
  {
    "id": 269,
    "empno": "34569",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34567",
    "extension": 345
  }
];

const hasDuplicates = (data) => {
  const set = new Set();
  
  for (let {empno, extension} of data) {
    const key = `${empno}/${extension}`;
    if (set.has(key)) {
      return true;
    }
    
    set.add(key);
  }
  
  return false;
};

console.log(hasDuplicates(data));

For a more concise solution that checks for duplicates by comparing the size of the array with a Set, you can use the following code snippet:

const hasDuplicates = (data) => data.length !== data.reduce((a, {empno, extension}) => a.add(`${empno}/${extension}`), new Set).size;

Complete code snippet:

const data = [{
    "id": 269,
    "empno": "34567",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34568",
    "extension": 346
  },
  {
    "id": 269,
    "empno": "34569",
    "extension": 345
  },
  {
    "id": 269,
    "empno": "34567",
    "extension": 345
  }
];

const hasDuplicates = (data) => data.length !== data.reduce((a, {empno, extension}) => a.add(`${empno}/${extension}`), new Set).size;

console.log(hasDuplicates(data));

Checking for duplicates in a TypeScript array of objects

Answer №1

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