Combine 2 arrays into 1 in all possible ways in JavaScript

Question

My goal is to merge 2 arrays in all possible ways, in a way that, the 1st array will always be the first part of the cell, and the 2nd array will always be in the 2nd part of the cell.
My last attempt, which is the closest but not exactly what I need:

function combineArrays(array1, array2) {
    let arr = [];
    for (let i = 0; i < array1.length; i++) {
        arr[i] = array1[i];
    }
    for (let i = 0, j = 0; i < array1.length; i++) {
        arr[i] += array2[j];
        if (array2[j + 1]) {
            j++;
        }
        else {
            j = 0;
        }
    }
    return arr;
}

Edit:
For example, array A and array B:
A: [ "I", "You", "He", "She" ]
B: [ "am", "is", "are" ]

Expected result:
[
"I am", "You am", "He am", "She am",
"I is", "You is', "He is", "She is",
"I are", "You are", "He are", "She are"
]

not sure what you need please post examples of array1, array2 and your expected output. — James, Jul 04 '17 at 18:15
Your code isn't really merging the arrays, its rather adding them up by index. — MinusFour, Jul 04 '17 at 18:15
That is not merging that is the [**Cartesian Product**](https://en.wikipedia.org/wiki/Cartesian_product) of the two arrays. — ibrahim mahrir, Jul 04 '17 at 18:37

MinusFour · Accepted Answer · 2017-07-04T18:48:32.867

2

let a = ["I", "You", "He", "She"];
let b = ["am", "is", "are"];
let result = b.map(b => a.map(a => a + ' ' + b));

console.log(result);

If you don't want the nested arrays:

let a = ["I", "You", "He", "She"];
let b = ["am", "is", "are"];
let result = b.reduce((arr, b) => arr.concat(a.map(a => a + ' ' + b)), []);

console.log(result);

For n amount of arrays:

    let a = ["I", "You", "He", "She"];
    let b = ["am", "is", "are"];
    let c = ["good", "bad", "happy"];
    let crossProduct = (a, b) => b.reduce((arr, b) => arr.concat(a.map(a => a + ' ' + b)), []);
    
    let result = [a, b, c].reduce(crossProduct);

    console.log(result);

edited Jul 04 '17 at 18:48

answered Jul 04 '17 at 18:28

MinusFour

13,913
3
30
39

The 2nd is perfect! Also, how can I do the same for X amount of arrays? – avi12 Jul 04 '17 at 18:40
@avi12, I updated the answer, all you got to do is put the arrays inside – MinusFour Jul 04 '17 at 18:49
Couldn't get a better answer! I can't thank you enough :) – avi12 Jul 04 '17 at 18:57
@MinusFour Many thanks for the `n` arrays example. You saved my morning. – Brandon Taylor Oct 12 '21 at 11:44

score 0 · Answer 2 · answered Jul 04 '17 at 18:14

var arr1 = ['a', 'b', 'c'];
var arr2 = ['d', 'e', 'f'];

var arr3 = arr1.concat(arr2);

// arr3 is a new array [ "a", "b", "c", "d", "e", "f" ]

but you seem you want to sum array that you achieve like this:

var array1 = [1,2,3,4];
var array2 = [5,6,7,8];

var sum = array1.map(function (num, idx) {
  return num + array2[idx];
}); 
// [6,8,10,12]

lebol · Answer 3 · 2017-07-04T18:36:20.153

0

If your goal is to merge two arrays, here is the ES6 way:

const arr1 = ['a', 'b', 'c'];
const arr2 = ['d', 'e', 'f'];

const arr3 = [...arr1, ...arr2]; // Output: [ "a", "b", "c", "d", "e", "f" ]

But, in your case (after your edit), you want to do more!

const arr1 = [ "I", "You", "He", "She" ];
const arr2 = [ "am", "is", "are" ];

arr2.map(eltB => arr1.map(eltA => `${eltA} ${eltB}`))
    .reduce((newArray, arr) => newArray.concat(arr), []);

edited Jul 04 '17 at 18:36

answered Jul 04 '17 at 18:15

lebol

433
5
12

Thanks! Also, how can I do the same for X amount of arrays? – avi12 Jul 04 '17 at 18:43

Combine 2 arrays into 1 in all possible ways in JavaScript

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