Functional Programming
We have been working on the City Explorer project for this module. Last lab we called third-party APIs to render live weather and movie data in response to city searches on our front-end App. This topic matters as it relates to understanding functional programming to refactor our code.
Functional Programming Concepts
What is functional programming?
Functional programming is a programming paradigm. A style of building the structure and elements of computer programs. Treats computation as the evaluation of mathematical functions and avoids changing state and mutable data.
What is a pure function and how do we know if something is a pure function?
It is a function that returns the same result if given the same arguments (also referred as deterministic). It does not cause any observable side effects. If it reads external files, it’s not a pure function.
What are the benefits of a pure function?
The code is easier to test. We don’t need to mock anything. We can unit test pure functions with different contexts:
- Given a parameter
A→ expect the function to return valueB - Given a parameter
C→ expect the function to return valueD
What is immutability?
Unchanging over time or unable to be changed. When data is immutable, its state cannot change after it is created. To change an immutable object we create a new object with the new value instead.
What is Referential transparency?
It is when a function consistently yields the same result for the same input.
pure functions + immutable data = referential transparency
Node JS - Modules and require()
What is a module?
A module is just another JS file.
What does the word ‘require’ do?
It is a function on the global object that we can use when we want to bring the same functionality from one JS file into a different file within our app.
How do we bring another module into the file the we are working in?
We use the require() function in the file that we are working in.
What do we have to do to make a module available?
We use the module.exports property in the JS file where the original function was created.
Things I want to know more about
- I would like to know more about how to implement functional programming to refactor my code and to practice more with modules and require().