JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr = [
    {"a": "x"},
    {"b": "0"},
    {"c": "k"},
    {"a": "nm"},
    {"b": "765"},
    {"ab": "i"},
    {"bc": "x"},
    {"ab": "4"},
    {"abc": "L"},
    {"dummy": "asdf"}
];

// Utility function to be used in the cartessian product
function flatten(arr) {
    return arr.reduce(function (memo, el) {
        return memo.concat(el);
    }, []);
}

// Utility function to be used in the cartessian product
function unique(arr) {
    return Object.keys(arr.reduce(function (memo, el) {
        return (memo[el] = 1) && memo;
    }, {}));
}

// It'll prepare the output in the expected way
function getObjArr(key, val, processedObj) {
    var set = function (key, val, obj) {
        return (obj[key] = val) && obj;
    };
    // The cartessian product is over so we can put the 'special case' in an object form so that we can get the expected output.
    return val !== 'repeated' ? [set(key, val, {})] : processedObj[key].reduce(function (memo, val) {
        return memo.concat(set(key, val, {}));
    }, []);
}

// This is the main function. It'll make the cartessian product.
var cartessianProdModified = (function (arr) {
    // Tweak the data model in order to have a set (key: array of values)
    var processedObj = arr.reduce(function (memo, obj) {
        var firstKey = Object.keys(obj)[0];
        return (memo[firstKey] = (memo[firstKey] || []).concat(obj[firstKey])) && memo;
    }, {});

    // Return a function that will perform the cartessian product of the args.
    return function (args) {
        // Spot repeated args.
        var countArgs = args.reduce(function (memo, el) {
                return (memo[el] = (memo[el] || 0) + 1) && memo;
            }, {}),
            // Remove repeated args so that the cartessian product works properly and more efficiently.
            uniqArgs = unique(args);

        return uniqArgs
                .reduce(function (memo, el) {
                    return flatten(memo.map(function (x) {
                        //...