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

## Problem Statement
Implement a function that sorts the input array `testVariable` *in-place*.

**In-place** means that no *extra* array or any other data structure is used in the algorithm. Such algorithms produce an output in the *same memory/space* that contains the data by transforming the input `in-place`. However, a *constant* amount of extra space can be used in the form of simple variables.

> Remember to solve this problem recursively.

### Input
1. An array `testVariable` containing numbers.
2. The length of the array.

### Output
No output. Our task is to sort the input array in ascending order.

### Sample Input
```javascript
testVariable = [5, 4, 2, 3, 1]
length = 5
```

### Sample Output
```javascript
// No explicit output. 
// However the state of array testVariable is [1, 2, 3, 4, 5]
```

### Try it Yourself
Try this challenge yourself before examining the solution. Good luck!

# Problem Statement
Implement a function that sorts the input array `testVariable` *in-place*.

**In-place** means that no *extra* array or any other data structure is used in the algorithm. Such algorithms produce an output in the *same memory/space* that contains the data by transforming the input `in-place`. However, a *constant* amount of extra space can be used in the form of simple variables.

> Remember to solve this problem recursively.

## Input
1. An array `testVariable` containing numbers.
2. The length of the array.

## Output
No output. Our task is to sort the input array in ascending order.

## Sample Input
```javascript
testVariable = [5, 4, 2, 3, 1]
length = 5
```

## Sample Output
```javascript
// No explicit output. 
// However the state of array testVariable is [1, 2, 3, 4, 5]
```

## Try it Yourself
Try this challenge yourself before examining the solution. Good luck!

Given an array of numbers, sort it in ascending order.

Recursion Fundamentals

Iteration Vs Recursion

Recursion with Numbers

Recursion with Strings

Recursion with Arrays

Recursion with Data Structures

Conclusion

Challenge 3: Sort an Array

Problem Statement

Input

Output

Sample Input

Sample Output

Try it Yourself