Merge corresponding elements from two arrays based on their indices

Question

Merge corresponding elements from two arrays based on their indices

If I have two arrays of objects structured like this:

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];

I am looking to merge them into a combined array as follows:

var arr3 = [{name: 'jay', age: 22}, {name: 'Bob', age: 30}];

It can be assumed that the indexes of the two initial arrays match each other, so index 0 of arr1 pairs with index 0 of arr2 consistently.

What is the most efficient method to achieve this? One possible approach could involve iterating over each array using nested forEach loops to combine objects from arr1 with their corresponding objects from arr2, but this may be overly complex.

javascript arrays object

Answer 1

Answer №1

One way to combine two arrays is to iterate through one array and create a new array using the index from the first iteration. There are multiple methods to achieve this. Here is an example:

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];

var combined = arr1.map(function(item, index) {
    return {name: item.name, age: arr2[index].age};
});
document.write(JSON.stringify(combined));

To optimize performance, testing different schemes in various browsers is necessary. For instance, in some cases, a 'for' loop may perform better than the built-in array methods in certain browsers.

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];
var combined = [];

for (var i = 0; i < arr1.length; i++) {
  combined[i] = {name: arr1[i].name, age: arr2[i].age};
}

document.write(JSON.stringify(combined));

Interestingly, the 'for' loop option (the second method) appears to be faster in all three browsers as seen in this jsperf experiment.

https://i.sstatic.net/PY3Ut.png

Answer 2

One way to combine two arrays is to iterate through one array and create a new array using the index from the first iteration. There are multiple methods to achieve this. Here is an example:

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];

var combined = arr1.map(function(item, index) {
    return {name: item.name, age: arr2[index].age};
});
document.write(JSON.stringify(combined));

To optimize performance, testing different schemes in various browsers is necessary. For instance, in some cases, a 'for' loop may perform better than the built-in array methods in certain browsers.

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];
var combined = [];

for (var i = 0; i < arr1.length; i++) {
  combined[i] = {name: arr1[i].name, age: arr2[i].age};
}

document.write(JSON.stringify(combined));

Interestingly, the 'for' loop option (the second method) appears to be faster in all three browsers as seen in this jsperf experiment.

https://i.sstatic.net/PY3Ut.png

Answer 3

Answer №2

Using a for loop to merge arrays:

var arr1 = [{name: 'Alice'}, {name: 'Dave'}];
var arr2 = [{age: 25}, {age: 28}];

for(var j in arr1)
{
  arr1[j]['age'] = arr2[j]['age'];
}

console.log(arr1) //[Object { name="Alice",  age=25}, Object { name="Dave",  age=28}]

After running the loop, arr1 now contains the merged data.

Answer 4

Using a for loop to merge arrays:

var arr1 = [{name: 'Alice'}, {name: 'Dave'}];
var arr2 = [{age: 25}, {age: 28}];

for(var j in arr1)
{
  arr1[j]['age'] = arr2[j]['age'];
}

console.log(arr1) //[Object { name="Alice",  age=25}, Object { name="Dave",  age=28}]

After running the loop, arr1 now contains the merged data.

Answer 5

Answer №3

The simplest approach stands out when compared to utility libraries like underscore.js. Its advantage lies in its independence from any external dependencies.

let mergedArray = [];
for(let i = 0; i < array1.length; i++) {
  let item = {};
  item.name = array1[i].name;
  item.age = array2[i].age;
  mergedArray.push(item);
}

Answer 6

The simplest approach stands out when compared to utility libraries like underscore.js. Its advantage lies in its independence from any external dependencies.

let mergedArray = [];
for(let i = 0; i < array1.length; i++) {
  let item = {};
  item.name = array1[i].name;
  item.age = array2[i].age;
  mergedArray.push(item);
}

Answer 7

Answer №4

An alternative method for achieving a loosely coupled solution is by utilizing the merge feature of the lodash library.

With this approach, you can seamlessly merge objects regardless of the number or names of keys present. This means that if you later decide to introduce new keys to your object, there is no need to modify the merging code.

var _ = require('lodash');

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];
var arr3 = [];

for (var i=0; i<arr1.length; i++) {
    arr3.push(_.merge(arr1[i], arr2[i]));
}

console.log(arr3);

Answer 8

An alternative method for achieving a loosely coupled solution is by utilizing the merge feature of the lodash library.

With this approach, you can seamlessly merge objects regardless of the number or names of keys present. This means that if you later decide to introduce new keys to your object, there is no need to modify the merging code.

var _ = require('lodash');

var arr1 = [{name: 'Jay'}, {name: 'Bob'}];
var arr2 = [{age: 22}, {age: 30}];
var arr3 = [];

for (var i=0; i<arr1.length; i++) {
    arr3.push(_.merge(arr1[i], arr2[i]));
}

console.log(arr3);

Merge corresponding elements from two arrays based on their indices

Answer №1

Answer №2

Answer №3

Answer №4

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