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Version: v1.4

✏️ 3.1.3.1 RPG Utilities, Haiku Checker (Two-day Project)

Goal: Choose one of the two projects below and work on it for both days. Pick whichever sounds more interesting to you — both will give you practice with closures, function factories, and composition. Try to incorporate the full range of tools you've learned in this section.

Warm Up​

  • What does it mean to mutate state? Why should we generally avoid this in functional programming?
  • What does it mean that functions are first class citizens?
  • What is a closure, and how do function factories use closures?

Code​

Option A: RPG Utilities​

Use function factories to build a set of weapon utilities for a simple RPG.

Weapon factory: Create a function factory that generates different weapons. Each weapon should take a base damage value and return the calculated damage:

const sword = createWeapon("Sword", 1.5); // multiplier of 1.5
const dagger = createWeapon("Dagger", 0.8); // multiplier of 0.8

sword(10);   // "Sword does 15 damage!"
dagger(10);  // "Dagger does 8 damage!"

Armor factory: Create a function factory that generates armor with different defense ratings. Armor should reduce incoming damage:

const leather = createArmor("Leather", 0.1); // reduces damage by 10%
const plate = createArmor("Plate", 0.5); // reduces damage by 50%

leather(20);  // "Leather absorbs 2 damage! You take 18 damage."
plate(20);    // "Plate absorbs 10 damage! You take 10 damage."

Bonus: Create a potion factory, spell factory, or another game element of your choice using the same pattern.

Option B: Haiku Checker/Creator​

Here's another project from Intermediate JavaScript — if you've already built this project, try refactoring your object-oriented approach so that it's functional instead. You may also choose to build a functional application from scratch.

A haiku is a poem that consists of three lines. The first has five syllables, the second has seven, and the third has five. Start by creating an application that checks whether a poem is in fact a haiku. If you have time, build out your application so that it can randomly generate haikus.

  • Your logic should verify that the poem has three lines.
  • Your logic should verify English syllable rules (and exceptions) one at a time. A quick Google search will provide information on English syllable rules.
  • If you successfully complete a Haiku checker, continue to build out your application to randomly generate haikus.

Make sure you test your application for each new rule you implement.

Instructor/Peer Code Review​

  • Code uses functional programming and avoids mutating state as much as possible.
  • Code demonstrates an understanding of closures and other functional concepts.
  • Application works as expected.
  • Code is well tested.