refactor: [#383] centralize random number generation

api/post-day-results.js

@@ -15,6 +15,7 @@ const {
   getRoomData,
   getRoomName,
 } = require('../api-etc/utils')
+const { random } = require('../src/common/utils')
 
 const client = getRedisClient()
 
@@ -30,7 +31,7 @@ const applyPositionsToMarket = (valueAdjustments, positions) => {
     (acc, itemName) => {
       const itemPositionChange = positions[itemName]
 
-      const variance = Math.random() * 0.2
+      const variance = random() * 0.2
 
       const MAX = 1.5
       const MIN = 0.5
@@ -43,7 +44,7 @@ const applyPositionsToMarket = (valueAdjustments, positions) => {
         // If item value is at a range boundary but was not changed in this
         // operation, randomize it to introduce some variability to the market.
         if (acc[itemName] === MAX || acc[itemName] === MIN) {
-          acc[itemName] = Math.random() + MIN
+          acc[itemName] = random() + MIN
         }
       }
 

src/common/utils.js

@@ -1,5 +1,10 @@
+/** @typedef {import("../index").farmhand.priceEvent} farmhand.priceEvent */
 import { itemsMap } from '../data/maps'
 
+export const random = () => {
+  return Math.random()
+}
+
 /**
  * @param {farmhand.priceEvent} [priceCrashes]
  * @param {farmhand.priceEvent} [priceSurges]
@@ -13,7 +18,7 @@ export const generateValueAdjustments = (priceCrashes = {}, priceSurges = {}) =>
       } else if (priceSurges[key]) {
         acc[key] = 1.5
       } else {
-        acc[key] = Math.random() + 0.5
+        acc[key] = random() + 0.5
       }
     }
 

src/components/CowPen/CowPen.js

@@ -13,9 +13,10 @@ import { pixel } from '../../img'
 import { getCowDisplayName, getCowImage } from '../../utils'
 
 import './CowPen.sass'
+import { random } from '../../common/utils'
 
 // Only moves the cow within the middle 80% of the pen
-const randomPosition = () => 10 + Math.random() * 80
+const randomPosition = () => 10 + random() * 80
 
 // TODO: Break this out into its own component file
 export class Cow extends Component {
@@ -155,7 +156,7 @@ export class Cow extends Component {
 
     this.repositionTimeoutId = setTimeout(
       this.repositionTimeoutHandler,
-      Math.random() * this.waitVariance
+      random() * this.waitVariance
     )
   }
 

src/components/Home/SnowBackground.js

@@ -2,8 +2,10 @@ import React from 'react'
 import useWindowSize from 'react-use/lib/useWindowSize'
 import Confetti from 'react-confetti'
 
+import { random } from '../../common/utils'
+
 const randomInt = (min, max) => {
-  return Math.floor(min + Math.random() * (max - min + 1))
+  return Math.floor(min + random() * (max - min + 1))
 }
 
 // Taken from:

src/game-logic/reducers/applyCrows.js

@@ -1,9 +1,9 @@
+import { random } from '../../common/utils'
 import { doesPlotContainCrop, isRandomNumberLessThan } from '../../utils'
 import { CROW_CHANCE, MAX_CROWS } from '../../constants'
 import { CROWS_DESTROYED } from '../../templates'
 
 import { modifyFieldPlotAt } from './modifyFieldPlotAt'
-
 import { fieldHasScarecrow } from './helpers'
 
 /**
@@ -47,12 +47,12 @@ export const applyCrows = state => {
 
   const numCrows = Math.min(
     plotsWithCrops.length,
-    Math.floor(Math.random() * (purchasedField + 1) * MAX_CROWS)
+    Math.floor(random() * (purchasedField + 1) * MAX_CROWS)
   )
   let numCropsDestroyed = 0
 
   for (let i = 0; i < numCrows; i++) {
-    const attackPlotId = Math.floor(Math.random() * plotsWithCrops.length)
+    const attackPlotId = Math.floor(random() * plotsWithCrops.length)
     const target = plotsWithCrops.splice(attackPlotId, 1)[0]
 
     state = modifyFieldPlotAt(state, target.x, target.y, () => null)

src/game-logic/reducers/generatePriceEvents.js

@@ -8,6 +8,7 @@ import {
 } from '../../utils'
 import { PRICE_EVENT_CHANCE } from '../../constants'
 import { PRICE_CRASH, PRICE_SURGE } from '../../templates'
+import { random } from '../../common/utils'
 
 import { createPriceEvent } from './createPriceEvent'
 
@@ -26,7 +27,7 @@ export const generatePriceEvents = state => {
 
   // TODO: Use isRandomNumberLessThan here once it supports an exclusive
   // less-than check.
-  if (Math.random() < PRICE_EVENT_CHANCE) {
+  if (random() < PRICE_EVENT_CHANCE) {
     const { items: unlockedItems } = getLevelEntitlements(
       levelAchieved(farmProductsSold(state.itemsSold))
     )
@@ -41,7 +42,7 @@ export const generatePriceEvents = state => {
     )
 
     if (!doesPriceEventAlreadyExist) {
-      const priceEventType = Math.random() < 0.5 ? TYPE_CRASH : TYPE_SURGE
+      const priceEventType = random() < 0.5 ? TYPE_CRASH : TYPE_SURGE
 
       priceEvent = createPriceEvent(
         state,

src/game-logic/reducers/minePlot.js

@@ -2,6 +2,7 @@ import { toolType } from '../../enums'
 import { chooseRandom, doesInventorySpaceRemain } from '../../utils'
 import { INVENTORY_FULL_NOTIFICATION } from '../../strings'
 import { ResourceFactory } from '../../factories'
+import { random } from '../../common/utils'
 
 import { addItemToInventory } from './addItemToInventory'
 import { showNotification } from './showNotification'
@@ -41,9 +42,7 @@ export const minePlot = (state, x, y) => {
     // if ore was spawned, add up to 10 days to the time to clear
     // at random, based loosely on the spawnChance meant to make
     // rarer ores take longer to cooldown
-    daysUntilClear += Math.round(
-      Math.random() * (1 - spawnedOre.spawnChance) * 10
-    )
+    daysUntilClear += Math.round(random() * (1 - spawnedOre.spawnChance) * 10)
 
     for (let resource of spawnedResources) {
       state = addItemToInventory(state, resource)

src/utils.js

@@ -76,6 +76,7 @@ import {
   STORM_CHANCE,
   STORAGE_EXPANSION_SCALE_PREMIUM,
 } from './constants'
+import { random } from './common/utils'
 
 const Jimp = configureJimp({
   types: [jimpPng],
@@ -96,7 +97,7 @@ const purchasableItemMap = [...cowShopInventory, ...shopInventory].reduce(
  * @return {number}
  */
 export const chooseRandomIndex = list =>
-  Math.round(Math.random() * (list.length - 1))
+  Math.round(random() * (list.length - 1))
 
 /**
  * @param {Array.<*>} list
@@ -499,7 +500,7 @@ export const generateCow = (options = {}) => {
     COW_STARTING_WEIGHT_BASE *
       (gender === genders.MALE ? MALE_COW_WEIGHT_MULTIPLIER : 1) -
       COW_STARTING_WEIGHT_VARIANCE +
-      Math.random() * (COW_STARTING_WEIGHT_VARIANCE * 2)
+      random() * (COW_STARTING_WEIGHT_VARIANCE * 2)
   )
 
   const cow = {
@@ -1191,7 +1192,7 @@ export function randomChoice(weightedOptions) {
 
   sortedOptions.sort(o => o.weight)
 
-  let diceRoll = Math.random() * totalWeight
+  let diceRoll = random() * totalWeight
   let option
   let runningTotal = 0
 
@@ -1309,8 +1310,8 @@ export const isInViewport = element => {
   )
 }
 
-export const shouldPrecipitateToday = () => Math.random() < PRECIPITATION_CHANCE
-export const shouldStormToday = () => Math.random() < STORM_CHANCE
+export const shouldPrecipitateToday = () => random() < PRECIPITATION_CHANCE
+export const shouldStormToday = () => random() < STORM_CHANCE
 
 /**
  * @param {farmhand.cow} cow

src/utils/isRandomNumberLessThan.js

@@ -1,8 +1,10 @@
+import { random } from '../common/utils'
+
 /**
  * Compares given number against a randomly generated number
  * @param {number} chance float between 0-1 to compare dice roll against
  * @returns {bool} true if the dice roll was equal to or lower than the given chance, false otherwise
  */
 export default function isRandomNumberLessThan(chance) {
-  return Math.random() <= chance
+  return random() <= chance
 }