Node.JS script for downloading minecraft assets

downloadMinecraftAssets.js

// downloadMinecraftAssets.js by HAHALOSAH
//
// Usage: node downloadMinecraftAssets.js <version>
//
// Sorry for the messy code, I made this in 10 minutes
// Requires node-fetch, run `npm i node-fetch' or `npm i -g node-fetch' first
// This script downloads assets for minecraft in the same format you would find in .minecraft/assets
// Defaults to latest version if not specified

const fs = require("fs");
const fetch = (...args) => import('node-fetch').then(({default: fetch}) => fetch(...args));

(async function() {
	async function download(url) {
		var req = await fetch(url);
		var res = await req.text();
		return res;
	}

	async function downloadBinary(url) {
		var req = await fetch(url);
		var res = await req.blob();
		return res;
	}

	async function downloadJson(url) {
		var req = await fetch(url);
		var res = await req.json();
		return res;
	}

	var VERSION_MANIFEST="https://launchermeta.mojang.com/mc/game/version_manifest.json";

	console.log("Downloading "+VERSION_MANIFEST);
	var versions = await downloadJson(VERSION_MANIFEST);
	var selectedVersion;
	if (process.argv[2] == undefined) {
		console.log("No version selected, defaulting to latest ("+versions.latest.release+")");
		selectedVersion = versions.latest.release;
	} else {
		selectedVersion = process.argv[2];
	}
	var versionInfo = versions.versions.find(v=>v.id==selectedVersion);
	if (versionInfo == undefined) {
		console.log("ERROR! Version not found!");
		process.exit(1);
	}
	console.log("Downloading "+versionInfo.url);

	var version = await downloadJson(versionInfo.url);
	console.log("Downloading "+version.assetIndex.url)
	var assetIndex = await download(version.assetIndex.url);
	//console.log(assetIndex)
	if (!fs.existsSync("assets")){
		fs.mkdirSync("assets");
	}
	if (!fs.existsSync("assets/indexes")){
		fs.mkdirSync("assets/indexes");
	}
	if (!fs.existsSync("assets/objects")){
		fs.mkdirSync("assets/objects");
	}
	fs.writeFileSync("assets/indexes/"+version.assetIndex.url.split("/").reverse()[0], assetIndex);

	function showPercentage(progress) {
		var columns = process.stdout.columns;
		var output = "["+("#".repeat(Math.round((columns-7)*progress)))+(".".repeat((columns-7)-Math.round((columns-7)*progress)))+"] "+Math.round(progress*100)+"%";
		process.stdout.write("\x1b[2K\r"+output);
	}
	function log(msg) {
		console.log("\x1b[2K\r"+msg);
	}
	assetIndex = JSON.parse(assetIndex);
	var keys = Object.keys(assetIndex.objects);
	var completed = 0;
	showPercentage(completed/keys.length);
	async function downloadAsset(name, hash) {
		var url = `http://resources.download.minecraft.net/${hash.substring(0,2)}/${hash}`;
		log("Downloading asset "+name+": "+url);
		showPercentage(completed/keys.length);
		var blob = await downloadBinary(url);
		if (!fs.existsSync("assets/objects/"+hash.substring(0,2))){
			fs.mkdirSync("assets/objects/"+hash.substring(0,2));
		}
		fs.writeFileSync("assets/objects/"+hash.substring(0,2)+"/"+hash, Buffer.from(await blob.arrayBuffer()));
		log("Downloaded asset "+name);
		completed += 1;
		showPercentage(completed/keys.length);
	}
	var p = [];
	keys.forEach(k=>p.push(downloadAsset(k,assetIndex.objects[k].hash)));
	await Promise.all(p);
	log("\nSaved assets to ./assets for version "+selectedVersion);

})();

Updated for the node-fetch update