reading-notes

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Refactoring

functional programming

Functional programming is a programming paradigm — a style of building the structure and elements of computer programs — that treats computation as the evaluation of mathematical functions and avoids changing-state and mutable data

Pure functions - It returns the same result if given the same arguments

Properties -

• It returns the same result if given the same arguments
• It does not cause any observable side effects

// global object that was not passed as a parameter to the function.
let PI = 3.14;

const calculateArea = (radius) => radius * radius * PI;

calculateArea(10); // returns 314.0


// This is a the pure function example
let PI = 3.14;

const calculateArea = (radius, pi) => radius * radius * pi;

calculateArea(10, PI); // returns 314.0

Immutability - Unchanging over time or unable to be changed.

strategies for easier code

• return early from functions
• Cache variables so functions can be read like sentences
• Check for Web APIs before implementing your own functionality

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