Introduction to the Functional Programming Challenges (freeCodeCamp)

What is Functional Programming?

According to freeCodeCamp, functional programming is an approach to software development based around the evaluation of functions. Like mathematics, functions in programming map input to output to produce a result. You can combine basic functions in many ways to build more and more complex programs.

Functional programming follows a few core principles:

• Functions are independent from the state of the program or global variables. They only depend on the arguments passed into them to make a calculation;

• Functions try to limit any changes to the state of the program and avoid changes to the global objects holding data;

• Functions have minimal side effects in the program.

The functional programming software development approach breaks a program into small, testable parts. This section covers basic functional programming principles in JavaScript.

Ordered Lessons & Answers

1. Learn About Functional Programming
2. Understand Functional Programming Terminology
3. Understand the Hazards of Using Imperative Code
4. Avoid Mutations and Side Effects Using Functional Programming
5. Pass Arguments to Avoid External Dependence in a Function
6. Refactor Global Variables Out of Functions
7. Use the map Method to Extract Data from an Array
8. Implement map on a Prototype
9. Use the filter Method to Extract Data from an Array
10. Implement the filter Method on a Prototype
11. Return Part of an Array Using the slice Method
12. Remove Elements from an Array Using slice Instead of splice
13. Combine Two Arrays Using the concat Method
14. Add Elements to the End of an Array Using concat Instead of push
15. Use the reduce Method to Analyze Data
16. Use Higher-Order Functions map, filter, or reduce to Solve a Complex Problem
17. Sort an Array Alphabetically using the sort Method
18. Return a Sorted Array Without Changing the Original Array
19. Split a String into an Array Using the split Method
20. Combine an Array into a String Using the join Method
21. Apply Functional Programming to Convert Strings to URL Slugs
22. Use the every Method to Check that Every Element in an Array Meets a Criteria
23. Use the some Method to Check that Any Elements in an Array Meet a Criteria
24. Introduction to Currying and Partial Application