Recursion

Recursion is a technique based on the divide and conquer principle. That principle calls for us to define the solution of a bigger problem in terms of the solution of a smaller version of itself.

In a programming language, a recursive function is one that calls itself. Let's look at the pseudo-code of a recursive function that prints the numbers from 1 to 5. You can invoke the function printList like printList(1).

The code is pretty cool as it will, like our iterative counterpart, also print the numbers 1, 2, 3, 4, 5. printList is a recursive function as it calls itself. We'll learn how it works in a bit.

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function printList(i) {

  // Base case: If i is greater than 5, return without doing anything

  if (i > 5) {

    return; // Do nothing

  }

  // Recursive case: Print the value of i

  console.log(i);

  // Call the function with i + 1

  printList(i + 1);

}