> For the complete documentation index, see [llms.txt](https://bryan-guner.gitbook.io/my-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://bryan-guner.gitbook.io/my-docs/job-search/interview-prep/interview-questions./what-is-functional-programming.md).

# What is functional programming?

## Answer

Functional programming is a paradigm in which programs are built in a declarative manner using pure functions that avoid shared state and mutable data. Functions that always return the same value for the same input and don't produce side effects are the pillar of functional programming. Many programmers consider this to be the best approach to software development as it reduces bugs and cognitive load.

## Good to hear

* Cleaner, more concise development experience
* Simple function composition
* Features of JavaScript that enable functional programming (`.map`, `.reduce` etc.)
* JavaScript is multi-paradigm programming language (Object-Oriented Programming and Functional Programming live in harmony)

### Additional links

* [Javascript and Functional Programming: An Introduction](https://hackernoon.com/javascript-and-functional-programming-an-introduction-286aa625e26d)
* [Master the JavaScript Interview: What is Functional Programming?](https://medium.com/javascript-scene/master-the-javascript-interview-what-is-functional-programming-7f218c68b3a0)