Array combinatorics in javascript, It's wrong?-CodePudding

I have created this script due to the need to perform unique combinations when I receive n number of arrays. It works, however when I want to store in a final array it writes something different.

let options = {
    "A": ["A1", "A2", "A3", "A4"],
    "B": ["B1", "B2"],
    "C": ["C1", "C2", "C3", "C4", "C5"],
};

let keys = Object.getOwnPropertyNames(options);
let size = keys.length;

let final = [];

function combinate(n, o) {

    for (let i = 0; i < options[keys[n]].length; i  ) {

        if (n === (size - 1)) {
            o = {};
        }

        o[keys[n]] = options[keys[n]][i];

        if ((n - 1) >= 0) {
            combinate(n - 1, o);
        }

        if (n === 0) {
            console.log(o);
            final.push(o);
        }

    }

}

if (size > 0) combinate(size - 1, {});

console.log("-----------------------------------")
console.log(final);

CodePudding user response：

You're saving a reference to the same object multiple times in your array, and making changes to that object. You need to clone the object before copying it into the array.

Change: final.push(o); to final.push(Object.assign({}, o));

CodePudding user response：

You need to pass the reference of the object into the function and then copy the modified object to the final array

let options = {
    "A": ["A1", "A2", "A3", "A4"],
    "B": ["B1", "B2"],
    "C": ["C1", "C2", "C3", "C4", "C5"], };

let keys = Object.getOwnPropertyNames(options); 
let size = keys.length;

let final = [];

function combinate(n, o, fooFinal) {

    for (let i = 0; i < options[keys[n]].length; i  ) {

        if (n === (size - 1)) {
            o = {};
        }

        o[keys[n]] = options[keys[n]][i];

        if ((n - 1) >= 0) {
            combinate(n - 1, o, fooFinal);
        }

        if (n === 0) {
            console.log(o);
            fooFinal.push(o);
        }

    }
    if(n===size-1){
      return fooFinal;
    }

}

if (size > 0){
  final = combinate(size - 1, {},[]);
}

console.log("-----------------------------------") 
console.log(final);