How to Generate All Combinations (Cartesian Product) of Values in JavaScript Arrays?

Cartesian Product of JavaScript Array Values

Problem:

Given an arbitrary number of JavaScript arrays of varying lengths, determine all combinations (Cartesian product) of their values.

Solution:

This task can be efficiently solved using recursion. It involves iterating through each array and combining its values with all possible combinations of the remaining arrays.

Consider the following implementation:

function allPossibleCases(arr) {
  if (arr.length === 1) {
    return arr[0];
  } else {
    const result = [];
    const casesOfRest = allPossibleCases(arr.slice(1));  // recur with the rest of arr
    casesOfRest.forEach((c) => {
      for (let i = 0; i < arr[0].length; i++) {
        result.push(arr[0][i] + c);
      }
    });
    return result;
  }
}

Usage:

var allArrays = [['a', 'b'], ['c'], ['d', 'e', 'f']];
var results = allPossibleCases(allArrays); // outputs ["acd", "bcd", "azd", ...]

Explanation:

• The allPossibleCases function takes an array of arrays as input.
• If the input array has only one sub-array, it returns its values.
• Otherwise, it recursively calls itself with the remaining sub-arrays and combines each sub-array value with all possible combinations of the remaining sub-arrays.
• The function iterates through each sub-array and concatenates its values with every combination from the remaining arrays, generating all possible combinations.
• The final result is an array of strings containing all the unique combinations of values from the input arrays.

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