Fibonacci Series using Recursion in Javascript

The Fibonacci series is a sequence of numbers in which each number after the first two is the sum of the two preceding numbers. In this tutorial, we will implement the Fibonacci series using recursion in JavaScript.

What is Recursion?

Recursion is a process in which a function calls itself as a subroutine. This allows the function to be repeated several times, making it useful for solving complex problems.

Implementing Fibonacci using Recursion

To implement the Fibonacci series using recursion, we first need to define the base case and recursive case for the function.

The base case is the simplest case that can be solved without recursion. In the case of the Fibonacci series, the base case is when n is less than or equal to 1. In this case, we simply return n as the result.

The recursive case is the more complex case that requires recursion to solve. In the case of the Fibonacci series, the recursive case is when n is greater than 1. In this case, we call the function recursively with the two preceding numbers in the series, and add the results together to get the current number in the series.

Here's the implementation of the Fibonacci series using recursion in JavaScript:

function fibonacci(n) {
  if (n <= 1) {
    return n;
  } else {
    return fibonacci(n - 1) + fibonacci(n - 2);
  }
}

Understanding the Code

Let's break down the code and understand how it works.

First, we define a function named fibonacci that takes a single argument n, which represents the index of the number in the Fibonacci series.

Next, we define the base case using an if statement. If n is less than or equal to 1, we simply return n as the result.

If n is greater than 1, we call the fibonacci function recursively with n - 1 and n - 2 as the arguments. This means that we are calling the fibonacci function with the two preceding numbers in the series. We then add the results of these two function calls together to get the current number in the series.

Finally, we return the result of the function call as the output.

Testing the Function

To test the function, we can call it with different values of n and check the output. Here's an example:

console.log(fibonacci(5)); // Output: 5
console.log(fibonacci(10)); // Output: 55
console.log(fibonacci(15)); // Output: 610

Conclusion

In this tutorial, we learned how to implement the Fibonacci series using recursion in JavaScript. Recursion can be a powerful tool for solving complex problems, but it's important to use it correctly to avoid performance issues or other problems.