The ultimate guide to recursion interviews in JavaScript. Developed by FAANG engineers. Practice with real-world interview questions and get interview-ready in just a few hours.

If you’ve ever struggled with solving problems using recursion, or if you have to brush up your skills for an interview, this course is for you.

We'll start with the basics of what recursion is and why it’s important before diving into practicing solving actual questions. You’ll have access to detailed explanations and visualizations for each problem to help you along the way. 

By the time you have completed this course, you’ll be able to use all the concepts to solve complex real-world problems. We hope that through practicing recursion, you will be able to ace all recursion related questions in interviews at top tech companies.

Recursion for Coding Interviews in JavaScript

# Solution #1: Multiplying Number with Itself

function findSquare(testVariable) {
  return testVariable * testVariable;
}

// Driver Code
var testVariable = 5;
console.log(findSquare(testVariable));

## Explanation
The solution to this problem is simple. We multiply the input variable with itself and return the result.

$$$$

# Solution #2: Recursive Method

## Explanation

Let's break the problem down mathematically. We'll compute the square of a number by direct recursion:

To implement the *square operation* as a *recursive function*, we need to first express the square operation in terms of itself:

Mathematically we know that:

$(n-1)^2 = n^2 - 2n + 1$

Let's isolate $n^2$ to one side of the equation and the rest of the components to the other side:

$n^2 = (n-1)^2 + 2n - 1$

This equation will be our **recursive case** while the $square$ of $0$ will be the **base case**:
```javascript
if (testVariable == 0) {
    return 0;
  }
```

The visualization below will help you better understand this code:

This review provides a detailed analysis of the ways to compute the square of a number.

Recursion Fundamentals

Iteration Vs Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Solution Review: Compute the Square of a Number

Solution #1: Multiplying Number with Itself

Explanation