Combine 2 Arrays Into 1 In All Possible Ways In Javascript

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 c

Solution 1:

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"];
    letcrossProduct = (a, b) => b.reduce((arr, b) => arr.concat(a.map(a => a + ' ' + b)), []);
    
    let result = [a, b, c].reduce(crossProduct);

    console.log(result);

Solution 2:

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

var arr3 = arr1.concat(arr2);

// arr3 is a newarray [ "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]

Solution 3:

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), []);