FP in JS 2

fp_js_2.js

// Create a person with a name
let simon = {"name": "simon"};

// Instead of copying simon, we assign it by reference.
// This is dangerous and can have unwanted behavior later.
let lisa = simon;

// Set the correct name of lisa
lisa.name = "lisa";

// But now we also updated simon's name!
console.log(simon); // { name: 'lisa' }

// If we would have copied simon, this would not have happened
// Let's see how we would do it in functional programming
let beth = {"name": "beth"};

// Copy beth instead of using a reference to it
let andy = {...beth};

// Set the correct name of andy
andy.name = "andy";

// Now both variables have the correct name
console.log(andy); // { name: 'andy' }
console.log(beth); // { name: 'beth' }