script.js

let spawn = require('child_process').spawn;
let rimraf = require("rimraf");
let fs = require("fs");

//command will be the first argument
let command = process.argv[2];
//args will be the array of arguments after the commands
let args = process.argv.slice(3).map(s => s.substr(2) === "--" ? s.substr(1) : s).filter(s => s !== '-w' && s !== '-watch');
//This is a boolean as to whether --watch or -w been in the commands
let watch = process.argv.map(s => s.substr(2) === "--" ? s.substr(1) : s).filter(s => s === '-w' || s === "-watch").length > 0;

Execute(command, args, watch).then();

//The decision on what command to execute base on the arguments and whether watch exists
async function Execute(command, args, watch) {
	let coverage = args.filter(s => s === "--cover").length > 0;
	switch (command) {
		case "wp":
			let wp = `webpack --config ./config/webpack.${args[0]}.ts`;
			if (watch) wp += " --watch";
			await run(wp);
			break;
		case "deploy":
			await run("node script test --cover");
			await run("node script wp dist");
			break;
		case "test":
			let mocha = `mocha -r ts-node/register --recursive ./test/**/*.spec.ts`;
			if (watch) mocha += " --watch-extensions ts --watch ";
			if (coverage) mocha = "nyc --nycrc-path ./config/.nycrc " + mocha;
			if (fs.existsSync("./.nyc_output")) rimraf.sync("./.nyc_output");
			await run(mocha);
			break;
		case "publish":
			await run(`npm version ${args[0]}`);
			await run(`npm publish`);
			break;
		default:
			console.log("Unknown command!");
			process.exit(1);
	}

}

//Executes the function as if its on the CMD. Exits the script if the external command crashes.
async function run(command) {
	if (!Array.isArray(command) && typeof command === "string") command = command.split(' ');
	else throw new Error("command is either a string or a string array");
	let c = command.shift();
	let v = command;

	let env = process.env;
	env.BROWSERSLIST_CONFIG = "./config/.browserslistrc";

	return new Promise((resolve) => spawn(c, v,
		{
			stdio: "inherit",
			shell: true,
			env: env
		})
		.on("exit", (code, signal) => {
			if (fs.existsSync("./.nyc_output")) rimraf.sync("./.nyc_output");
			if (code === 0) resolve();
			else {
				console.log("ExternalError:", signal);
				process.exit(1);
			}
		})
	);
}