Matrix Permutation Function

generateMatrix.js

'use strict';
var clone = require('clone');

function generateMatrixHelper(options, currentSettings, keysToIterate, keyIndexer, permutations) {
    if (keysToIterate.every((optionKey) => currentSettings[optionKey])) {
        permutations.push(currentSettings);
        return;
    }

    if (keyIndexer >= keysToIterate.length) {
        return;
    }

    let keyToAdd = keysToIterate[keyIndexer];
    keyIndexer += 1;

    options[keyToAdd].forEach( (value) => {
        currentSettings[keyToAdd] = value;
        return generateMatrixHelper(options, clone(currentSettings), keysToIterate, keyIndexer, permutations);
    });
}

function generateMatrix(options) {
    let thing = {};
    let settings = {};
    let perms = []

    let keysToIterate = Object.keys(options);
    let keyIndexer = 0;
    let keyToStart = keysToIterate[keyIndexer];

    options[keyToStart].forEach( (value) => {
        // set { v: 1 } and then { v: 2 }
       thing[keyToStart] = value;
       return generateMatrixHelper(options, clone(thing), keysToIterate, 1, perms)
    });

    return perms;
}

let obj = {
    x: [1,2],
    // y: ['a', 'b'],
    // z: ['c', 'd'],
    a: ['e', 'f', 'g']
    // b: [3]
}

console.log(generateMatrix(obj));

Outputs:

[ { x: 1, a: 'e' },
  { x: 1, a: 'f' },
  { x: 1, a: 'g' },
  { x: 2, a: 'e' },
  { x: 2, a: 'f' },
  { x: 2, a: 'g' } ]