automatically exporting a module with koa (possibly insecure)

mymod.js

exports.bah=function(count,name){
	let out="";
	while(count--)
		out+=name+" ";
	return out;
};

server.js

// Install requirements with: npm install --save co co-body koa-better-router koa@2

const app=new (require("koa"))();
const router=require("koa-better-router")().loadMethods();
const co_body=require("co-body");
const mymod=require("./mymod");

// Test the below with: curl -d "[3,\"Hello\"]" http://localhost:8080/mymod/bah

router.post("/mymod/:myfun",function*() {
	const fun=this.route.params.myfun;
	const args=yield co_body.json(this,{limit:"10kb"});
	const mod=mymod;
	// Only allow invoking direct properties on the object (ie restrict the prototype chain methods from being invoked)
	if (Object.prototype.hasOwnProperty.call(mod,fun)) {
		this.body=mod[fun].apply(null,args);
	} else {
		this.body="No such method "+fun;
	}
});

app.use(router.middleware());

app.listen(8080);