recursiveProdArrayElement.js

// recursion 1 - using helper function
const RecursiveHelperProductArr = (arr) => {
    let index = arr.length - 1;

    // helper function
    const recur = (curIndex, acc) => { 
      acc *= arr[curIndex];
      if (curIndex === 0) return acc;
      return recur(curIndex - 1, acc); // decrement the index and recursion
    }
  
    return recur(index, 1);
}

// recursion 2 - using built-in slice
const RecursiveSliceProductArr = (arr) => {
    return (arr.length === 0) ? 1 : arr[0] * RecursiveSliceProductArr(arr.slice(1));
}


const arr = [1,2,3,4,5]; // ==> 120

console.log(RecursiveHelperProductArr(arr));
console.log(RecursiveSliceProductArr(arr));