├── countDown.js
├── factorial.js
├── helperMethodRecursion.js
├── pureRecursion.js
└── sumRange.js


/countDown.js:
--------------------------------------------------------------------------------
 1 | function countDown(num) {
 2 |   if (num <= 0) {
 3 |     console.log("All done!");
 4 |     return;
 5 |   }
 6 |   console.log(num);
 7 |   num--;
 8 |   countDown(num);
 9 | }
10 | 
11 | countDown(5);
12 | 


--------------------------------------------------------------------------------
/factorial.js:
--------------------------------------------------------------------------------
1 | function factorial(num) {
2 |   if (num === 1) return 1;
3 |   return num * factorial(num - 1);
4 | }
5 | 
6 | console.log(factorial(5));
7 | 


--------------------------------------------------------------------------------
/helperMethodRecursion.js:
--------------------------------------------------------------------------------
 1 | function collectOddValues(arr) {
 2 |   let result = [];
 3 | 
 4 |   function helper(input) {
 5 |     if (input.length === 0) return;
 6 |     if (input[0] % 2 !== 0) {
 7 |       result.push(input[0]);
 8 |     }
 9 |     helper(input.slice(1));
10 |   }
11 |   helper(arr);
12 |   return result;
13 | }
14 | 
15 | console.log(collectOddValues([1, 2, 3, 4, 5, 6, 7, 8, 9]));
16 | 


--------------------------------------------------------------------------------
/pureRecursion.js:
--------------------------------------------------------------------------------
 1 | function collectOddValues(arr) {
 2 |   let newArr = [];
 3 |   if (arr.length === 0) {
 4 |     return newArr;
 5 |   }
 6 |   if (arr[0] % 2 !== 0) {
 7 |     newArr.push(arr[0]);
 8 |   }
 9 |   newArr = newArr.concat(collectOddValues(arr.slice(1)));
10 |   return newArr;
11 | }
12 | 
13 | console.log(collectOddValues([1, 2, 3, 4, 5, 6, 7, 8, 9]));
14 | 


--------------------------------------------------------------------------------
/sumRange.js:
--------------------------------------------------------------------------------
1 | function sumRange(num) {
2 |   if (num === 1) return 1;
3 |   return num + sumRange(num - 1);
4 | }
5 | 
6 | console.log(sumRange(5));
7 | console.log(sumRange(4));
8 | console.log(sumRange(3));
9 | 


--------------------------------------------------------------------------------