TypeScript - all possible combinations for 2D array items

const detectCombinations = (input: string[][], output: string[][], position?: number, path?: string[]): void => {

  if (position == null) {

    position = 0;

  }

  if (path == null) {

    path = [];

  }

  if (position < input.length) {

    const item = input[position];

    for (let i = 0; i < item.length; ++i) {

      const value = item[i];

      path.push(value);

      detectCombinations(input, output, position + 1, path);

      path.pop();

    }

  } else {

    output.push(path.slice());

  }

};

​

// Helper methods:

​

const printArray = (array: string[][]): void => {

  for (let i = 0; i < array.length; ++i) {

    console.log(array[i].join(' '));

  }

};

​

// Usage example:

​

const input: string[][] = [

  ['a', 'b', 'c'],

  ['d', 'e'],

  ['w', 'x', 'y', 'z'],

];

​

const output: string[][] = [];

​

detectCombinations(input, output);

printArray(output);

a 1 w

a 1 x

a 1 y

a 1 z

a 2 w

a 2 x

a 2 y

a 2 z

b 1 w

b 1 x

b 1 y

b 1 z

b 2 w

b 2 x

b 2 y

b 2 z

c 1 w

c 1 x

c 1 y

c 1 z

c 2 w

c 2 x

c 2 y

c 2 z