freeCodeCamp/curriculum/challenges/english/02-javascript-algorithms-and-data-structures/functional-programming/learn-about-functional-programming.md

id, title, challengeType, forumTopicId, dashedName

id	title	challengeType	forumTopicId	dashedName
587d7b8d367417b2b2512b5b	Learn About Functional Programming	1	301233	learn-about-functional-programming

--description--

Functional programming is a style of programming where solutions are simple, isolated functions, without any side effects outside of the function scope.

INPUT -> PROCESS -> OUTPUT

Functional programming is about:

1. Isolated functions - there is no dependence on the state of the program, which includes global variables that are subject to change

2. Pure functions - the same input always gives the same output

3. Functions with limited side effects - any changes, or mutations, to the state of the program outside the function are carefully controlled

--instructions--

The members of freeCodeCamp happen to love tea.

In the code editor, the prepareTea and getTea functions are already defined for you. Call the getTea function to get 40 cups of tea for the team, and store them in the tea4TeamFCC variable.

--hints--

The tea4TeamFCC variable should hold 40 cups of tea for the team.

assert(tea4TeamFCC.length === 40);

The tea4TeamFCC variable should hold cups of green tea.

assert(tea4TeamFCC[0] === 'greenTea');

--seed--

--seed-contents--

// Function that returns a string representing a cup of green tea
const prepareTea = () => 'greenTea';

/*
Given a function (representing the tea type) and number of cups needed, the
following function returns an array of strings (each representing a cup of
a specific type of tea).
*/
const getTea = (numOfCups) => {
  const teaCups = [];

  for(let cups = 1; cups <= numOfCups; cups += 1) {
    const teaCup = prepareTea();
    teaCups.push(teaCup);
  }
  return teaCups;
};

// Only change code below this line
const tea4TeamFCC = null;
// Only change code above this line

--solutions--

const prepareTea = () => 'greenTea';

const getTea = (numOfCups) => {
  const teaCups = [];
  
  for(let cups = 1; cups <= numOfCups; cups += 1) {
    const teaCup = prepareTea();
    teaCups.push(teaCup);
  }

  return teaCups;
};

const tea4TeamFCC = getTea(40);