Undertale Randomizer (MAC)

index.js

/*
Note: this node.js script will only work on mac with the steam version of the game, sorry about that.
MAKE A BACKUP BEFORE RUNNING
To make a backup: Copy the files in your undertale resources folder to a new folder somewhere safe
  To find your resources folder:
    - Open Finder
    - Press Command + G
    - Paste ~/Library/Application Support/Steam/steamapps/common/Undertale/UNDERTALE.app/Contents/Resources
*/

const fs = require('fs')
const path = require('path')

const resources = path.resolve(process.env.HOME, "Library", "Application Support", "Steam", "steamapps", "common", "Undertale", "UNDERTALE.app", "Contents", "Resources")
const files = fs.readdirSync(resources)

let music = []

files.forEach((file) => {
    if (file.startsWith("mus_") || file.startsWith("TMP-mus_")) {
        music.push(file.replace("TMP-", ""))
    }
})

let shuffled = music
.map(value => ({ value, sort: Math.random() }))
.sort((a, b) => a.sort - b.sort)
.map(({ value }) => value)

// Prevent naming conflicts
for (let index = 0; index < music.length; index++) {
    const file = music[index];
    if (!file.startsWith("TMP-")) {
        try {
            fs.renameSync(`${resources}/${file}`, `${resources}/TMP-${file}`)
        } catch(e) {console.error(e)}
    }
}

// Actually randomize it
for (let masterIndex = 0; masterIndex < music.length; masterIndex++) {
    fs.renameSync(`${resources}/TMP-${music[masterIndex]}`, `${resources}/${shuffled[masterIndex]}`)
}

console.log("All done!")