What is the most effective method for merging two arrays in JavaScript?

Question

What is the most effective method for merging two arrays in JavaScript?

Can a function be created to generate an array like the following?

["0-AA", "0-BB", "1-AA", "1-BB", "2-AA", "2-BB", "3-AA", "3-BB"]

This particular function combines two arrays with a separator '-' as shown below:

arr1 = [0,1,2,3]    //numbers
arr2 = ["AA", "BB"]  //codes

The resulting array length is always the product of the lengths of the two input arrays. Both arrays can vary in size and the first array always contains integers.

I'm looking for an elegant way to combine these arrays without using loops or repetitive statements. Can this be achieved using only array functions like map, concat, etc.?

javascript typescript

Answer 1

Answer №1

This technique is known as the Cartesian product, and it involves using one loop per array. In this code snippet, the map and flatMap functions are utilized to achieve this.

function calculateProduct(array1, array2, separator) {
  return array1.flatMap(elementArr => array2.map(subElement => elementArr + separator + subElement))
}

const firstArray = [0,1,2,3]
const secondArray = ["AA", "BB"]
const result = calculateProduct(firstArray, secondArray, "-")
console.log(result)

Alternatively, a more versatile version of the function called product can handle any number of arrays and generate tuples that can be joined manually. The use of an extra loop provided by the reduce method helps iterate over the input arrays.

function product(...arrays) {
  return arrays.reduce(
    (result, currentArray) =>
      result.flatMap(res =>
        currentArray.map(arrElement => res.concat([arrElement]))
      ),
    [[]],
  )
}

const array1 = [0,1,2,3]
const array2 = ["AA", "BB"]
const output = product(array1, array2).map(items => items.join('-'))
console.log(output)

Answer 2

This technique is known as the Cartesian product, and it involves using one loop per array. In this code snippet, the map and flatMap functions are utilized to achieve this.

function calculateProduct(array1, array2, separator) {
  return array1.flatMap(elementArr => array2.map(subElement => elementArr + separator + subElement))
}

const firstArray = [0,1,2,3]
const secondArray = ["AA", "BB"]
const result = calculateProduct(firstArray, secondArray, "-")
console.log(result)

Alternatively, a more versatile version of the function called product can handle any number of arrays and generate tuples that can be joined manually. The use of an extra loop provided by the reduce method helps iterate over the input arrays.

function product(...arrays) {
  return arrays.reduce(
    (result, currentArray) =>
      result.flatMap(res =>
        currentArray.map(arrElement => res.concat([arrElement]))
      ),
    [[]],
  )
}

const array1 = [0,1,2,3]
const array2 = ["AA", "BB"]
const output = product(array1, array2).map(items => items.join('-'))
console.log(output)

Answer 3

Answer №2

To achieve this, you can leverage the power of .reduce and .forEach

list1 = [....]
list2 = [....]

newList = list1.reduce((accumulator, element) => {
  list2.forEach(item => accumulator.push(`${element}-${item}`))
  return accumulator;
}, [])

Answer 4

To achieve this, you can leverage the power of .reduce and .forEach

list1 = [....]
list2 = [....]

newList = list1.reduce((accumulator, element) => {
  list2.forEach(item => accumulator.push(`${element}-${item}`))
  return accumulator;
}, [])

Answer 5

Answer №3

Although following the demonstrated method is an option

const numbers = [4, 5, 6]
const letters = ['x', 'y', 'z']

const result = numbers
    .reduce((result, value1) => (
        result.push(letters.map(value2 => value1 + '-' + value2)),
        result), [])
    .flat()

I recommend utilizing a more traditional function with for loops to achieve a slight performance boost in both speed and memory usage.

function generateProduct(numbers, letters, separator = '') {
    const product = []
    for (let i = 0; i < numbers.length; ++i)
        for (let j = 0; j < letters.length; ++j)
            product.push(numbers[i] + separator + letters[j])
    return product
}

Answer 6

Although following the demonstrated method is an option

const numbers = [4, 5, 6]
const letters = ['x', 'y', 'z']

const result = numbers
    .reduce((result, value1) => (
        result.push(letters.map(value2 => value1 + '-' + value2)),
        result), [])
    .flat()

I recommend utilizing a more traditional function with for loops to achieve a slight performance boost in both speed and memory usage.

function generateProduct(numbers, letters, separator = '') {
    const product = []
    for (let i = 0; i < numbers.length; ++i)
        for (let j = 0; j < letters.length; ++j)
            product.push(numbers[i] + separator + letters[j])
    return product
}

Answer 7

Answer №4

Looking at your final request,

Can we use array-only methods like map, concat, etc. without resorting to repetitive statements like for loops?

I'm assuming you are okay with array.forEach().

const array1 = [10, 20, 30];
const array2 = ["red", "blue"];

const resultArr = [];

array1.forEach((num)=>{
  array2.forEach((color)=>{
    resultArr.push(`${num}-${color}`);
  });
});

console.log(resultArr);

Answer 8

Looking at your final request,

Can we use array-only methods like map, concat, etc. without resorting to repetitive statements like for loops?

I'm assuming you are okay with array.forEach().

const array1 = [10, 20, 30];
const array2 = ["red", "blue"];

const resultArr = [];

array1.forEach((num)=>{
  array2.forEach((color)=>{
    resultArr.push(`${num}-${color}`);
  });
});

console.log(resultArr);

What is the most effective method for merging two arrays in JavaScript?

Answer №1

Answer №2

Answer №3

Answer №4

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