What is the most efficient way to add a new object to an array in JavaScript by searching for a specific object in a separate array and returning a distinct object

Question

What is the most efficient way to add a new object to an array in JavaScript by searching for a specific object in a separate array and returning a distinct object

Looking to merge two JavaScript object arrays similar to a vlookup function in Excel. The goal is to match objects from one array with another, and then combine them into a single array for streamlined access.

For instance,

    let array1 = [
        {"first":"Ana","last":"Anderson","id":"0001"},
        {"first":"Bob","last":"Brown","id":"0002"},
        {"first":"Charlie","last":"Clark","id":"0003"},
        {"first":"Danielle","last":"Dunn","id":"0004"}
    ]

    let array2 = [
        {"age":"38","id":"0002","eyeColor":"hazel","hieght":"5.5"},
        {"age":"45","id":"0001","eyeColor":"brown","hieght":"5"},
        {"age":"23","id":"0003","eyeColor":"blue","hieght":"6"}
    ]

How can I create an array that merges the data like this?

let array3 = [
        {"first":"Ana","last":"Anderson","id":"0001","age":"45","eyeColor":"brown","height":"5"},
        {"first":"Bob","last":"Brown","id":"0002","age":"38","eyeColor":"hazel","height":"5.5"},
        {"first":"Charlie","last":"Clark","id":"0003","age":"23","eyeColor":"blue","height":"6"},
        {"first":"Danielle","last":"Dunn","id":"0004","age":"","eyeColor":"","height":""}
    ]

javascript arrays for-loop indexof

Answer 1

Answer №1

Create an empty object as a placeholder for no matches
Map all new objects from array2 based on their ids
Loop through array1 and update items using the mapped values or the empty object

let array1 = [
    {"first":"Anna","last":"Adams","id":"0005"},
    {"first":"Ben","last":"Barker","id":"0006"},
    {"first":"Cara","last":"Collins","id":"0007"}
]

let array2 = [
    {"age":"28","id":"0007","eyeColor":"green","height":"6.1"},
    {"age":"33","id":"0005","eyeColor":"blue","height":"5.8"},
    {"age":"40","id":"0006","eyeColor":"brown","height":"5.9"}
];

const blankObject = Object.keys(array2[0]).reduce((result, key) => (key !== 'id' && (result[key] = ''), result), {});
const mapping = array2.reduce((result, item) => (result[item.id] = item, result), {});
array1.forEach(item => Object.assign(item, mapping[item.id] ?? blankObject));

console.log(array1);

Answer 2

Create an empty object as a placeholder for no matches
Map all new objects from array2 based on their ids
Loop through array1 and update items using the mapped values or the empty object

let array1 = [
    {"first":"Anna","last":"Adams","id":"0005"},
    {"first":"Ben","last":"Barker","id":"0006"},
    {"first":"Cara","last":"Collins","id":"0007"}
]

let array2 = [
    {"age":"28","id":"0007","eyeColor":"green","height":"6.1"},
    {"age":"33","id":"0005","eyeColor":"blue","height":"5.8"},
    {"age":"40","id":"0006","eyeColor":"brown","height":"5.9"}
];

const blankObject = Object.keys(array2[0]).reduce((result, key) => (key !== 'id' && (result[key] = ''), result), {});
const mapping = array2.reduce((result, item) => (result[item.id] = item, result), {});
array1.forEach(item => Object.assign(item, mapping[item.id] ?? blankObject));

console.log(array1);

Answer 3

Answer №2

Employ a loop to cycle through array1 and match the id of each element in array1 with objects in array2 to combine the data.

let array1 = [
    {"first":"Ana","last":"Anderson","id":"0001"},
    {"first":"Bob","last":"Brown","id":"0002"},
    {"first":"Charlie","last":"Clark","id":"0003"},
    {"first":"Danielle","last":"Dunn","id":"0004"}
];

let array2 = [
    {"age":"38","id":"0002","eyeColor":"hazel","hieght":"5.5"},
    {"age":"45","id":"0001","eyeColor":"brown","hieght":"5"},
    {"age":"23","id":"0003","eyeColor":"blue","hieght":"6"}
];

let array3 = [];

for (let i = 0; i < array1.length; i++) {
    let matchedObject = array2.find(obj => obj.id === array1[i].id) || {};
  
    let mergedObject = { ...array1[i], ...matchedObject };
    
    array3.push(mergedObject);
}

console.log(array3);

Answer 4

Employ a loop to cycle through array1 and match the id of each element in array1 with objects in array2 to combine the data.

let array1 = [
    {"first":"Ana","last":"Anderson","id":"0001"},
    {"first":"Bob","last":"Brown","id":"0002"},
    {"first":"Charlie","last":"Clark","id":"0003"},
    {"first":"Danielle","last":"Dunn","id":"0004"}
];

let array2 = [
    {"age":"38","id":"0002","eyeColor":"hazel","hieght":"5.5"},
    {"age":"45","id":"0001","eyeColor":"brown","hieght":"5"},
    {"age":"23","id":"0003","eyeColor":"blue","hieght":"6"}
];

let array3 = [];

for (let i = 0; i < array1.length; i++) {
    let matchedObject = array2.find(obj => obj.id === array1[i].id) || {};
  
    let mergedObject = { ...array1[i], ...matchedObject };
    
    array3.push(mergedObject);
}

console.log(array3);

Answer 5

Answer №3

Instead of utilizing the index values, it is more advantageous to create a Map and utilize the id as the key. Proceed to iterate through the second object, comparing the id with the map's key. If there is a match, you can then append those properties from the second array to the corresponding object in the first array.

let array1 = [{
    "first": "Ana",
    "last": "Anderson",
    "id": "0001"
  },
  {
    "first": "Bob",
    "last": "Brown",
    "id": "0002"
  },
  {
    "first": "Charlie",
    "last": "Clark",
    "id": "0003"
  },
  {
    "first": "Danielle",
    "last": "Dunn",
    "id": "0004"
  }
]

let array2 = [{
    "age": "38",
    "id": "0002",
    "eyeColor": "hazel",
    "height": "5.5"
  },
  {
    "age": "45",
    "id": "0001",
    "eyeColor": "brown",
    "height": "5"
  },
  {
    "age": "23",
    "id": "0003",
    "eyeColor": "blue",
    "height": "6"
  }
];
// initiate a new map object
const map1 = new Map();
//iterate through each element in the array and store the value in the map
array1.forEach(item => {
  map1.set(item.id, item)
});
// iterate through elements in array2 and verify if they exist in map1, if so then update 
// the object by combining the properties from both arrays
array2.forEach(item => {
  map1.has(item.id) && map1.set(item.id, { ...map1.get(item.id),
    ...item
  })

});
console.log(Array.from(map1.values()))

Answer 6

Instead of utilizing the index values, it is more advantageous to create a Map and utilize the id as the key. Proceed to iterate through the second object, comparing the id with the map's key. If there is a match, you can then append those properties from the second array to the corresponding object in the first array.

let array1 = [{
    "first": "Ana",
    "last": "Anderson",
    "id": "0001"
  },
  {
    "first": "Bob",
    "last": "Brown",
    "id": "0002"
  },
  {
    "first": "Charlie",
    "last": "Clark",
    "id": "0003"
  },
  {
    "first": "Danielle",
    "last": "Dunn",
    "id": "0004"
  }
]

let array2 = [{
    "age": "38",
    "id": "0002",
    "eyeColor": "hazel",
    "height": "5.5"
  },
  {
    "age": "45",
    "id": "0001",
    "eyeColor": "brown",
    "height": "5"
  },
  {
    "age": "23",
    "id": "0003",
    "eyeColor": "blue",
    "height": "6"
  }
];
// initiate a new map object
const map1 = new Map();
//iterate through each element in the array and store the value in the map
array1.forEach(item => {
  map1.set(item.id, item)
});
// iterate through elements in array2 and verify if they exist in map1, if so then update 
// the object by combining the properties from both arrays
array2.forEach(item => {
  map1.has(item.id) && map1.set(item.id, { ...map1.get(item.id),
    ...item
  })

});
console.log(Array.from(map1.values()))

What is the most efficient way to add a new object to an array in JavaScript by searching for a specific object in a separate array and returning a distinct object

Answer №1

Answer №2

Answer №3

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