recursion

// 1. ID base case
// 2. ID recursive case
// 3. Return where appropriate
// 4. Write procedures that bring you closer to base case

// Simple factorial example with Recursion
const factorial = n => {
  return n < 2 ? 1 : n * factorial(n - 1);
};

console.log(factorial(1));
console.log(factorial(2));
console.log(factorial(3));
console.log(factorial(4));
console.log(factorial(5));

// Walking a tree
function walkTree(node) {
  if (node == null) return;

  for (var i = 0; i < node.childNodes.length; i++) {
    walkTree(node.childNodes[i]);
  }
}

// Recursion sets up a FUNCTION STACK
function foo(i) {
  if (i < 0) return;
  console.log("begin: " + i);

  foo(i - 1);
  console.log("end: " + i);
}
foo(3);