What is the best method for combining multiple arrays of objects without any duplicate elements?

Question

What is the best method for combining multiple arrays of objects without any duplicate elements?

I have been trying to solve this issue, but all the solutions I found assume that you know the number of arrays you want to merge without duplicates.

My task is to iterate over an object containing multiple arrays. Each array holds objects structured as follows:

{sType: string, nLaId: number, sname: string}

. To determine if an object is a duplicate, I need to compare it with other objects based on both sType and nLaId.

for(let key in objectContainingArrays){
  // How can I efficiently merge these arrays without duplicating any objects?
}

If there is a straightforward solution or if this question has already been answered elsewhere, I apologize and would be grateful for a link. Thank you!

javascript arrays typescript merge duplicates

Answer 1

Answer №1

If you're not utilizing any libraries such as underscore.js, one way to handle arrays is by first merging them and then removing any duplicates:

var mergedArray = [].concat.apply([], arrList);

var uniqueArray = mergedArray.filter((currentValue, index, arr) => 
  arr.findIndex (
     arrItem => (
        arrItem.sType === currentValue.sType && arrItem.nLaId === currentValue.nLaId)
     ) === index
);

Here's a sample scenario -

var arr1 = [{
    sType: "S1",
    nLaId: 1,
    sname: "N1"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N2"
  },
  {
    sType: "S3",
    nLaId: 3,
    sname: "N3"
  }
];
var arr2 = [{
    sType: "S2",
    nLaId: 2,
    sname: "N4"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N5"
  },
  {
    sType: "S1",
    nLaId: 3,
    sname: "N6"
  },
  {
    sType: "S4",
    nLaId: 3,
    sname: "N7"
  }
];
var arr3 = [{
    sType: "S1",
    nLaId: 1,
    sname: "N8"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N9"
  }
];

var arrList = [arr1, arr2, arr3];
var mergedArray = [].concat.apply([], arrList);
var uniqueArray = mergedArray.filter((currentValue, index, arr) => 
arr.findIndex(arrItem => (arrItem.sType === currentValue.sType && arrItem.nLaId === currentValue.nLaId)) === index);

console.log(uniqueArray);

Answer 2

If you're not utilizing any libraries such as underscore.js, one way to handle arrays is by first merging them and then removing any duplicates:

var mergedArray = [].concat.apply([], arrList);

var uniqueArray = mergedArray.filter((currentValue, index, arr) => 
  arr.findIndex (
     arrItem => (
        arrItem.sType === currentValue.sType && arrItem.nLaId === currentValue.nLaId)
     ) === index
);

Here's a sample scenario -

var arr1 = [{
    sType: "S1",
    nLaId: 1,
    sname: "N1"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N2"
  },
  {
    sType: "S3",
    nLaId: 3,
    sname: "N3"
  }
];
var arr2 = [{
    sType: "S2",
    nLaId: 2,
    sname: "N4"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N5"
  },
  {
    sType: "S1",
    nLaId: 3,
    sname: "N6"
  },
  {
    sType: "S4",
    nLaId: 3,
    sname: "N7"
  }
];
var arr3 = [{
    sType: "S1",
    nLaId: 1,
    sname: "N8"
  },
  {
    sType: "S2",
    nLaId: 2,
    sname: "N9"
  }
];

var arrList = [arr1, arr2, arr3];
var mergedArray = [].concat.apply([], arrList);
var uniqueArray = mergedArray.filter((currentValue, index, arr) => 
arr.findIndex(arrItem => (arrItem.sType === currentValue.sType && arrItem.nLaId === currentValue.nLaId)) === index);

console.log(uniqueArray);

What is the best method for combining multiple arrays of objects without any duplicate elements?

Answer №1

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