gistfile1.txt

//register.ts
export class Register {

    validateEmail(email){
    	return false;
    }
    
    onPostCheckMail (req, res) {
    	if(this.validateEmail(req.body.email) === true){ //validateEmail is undefined
	  		res.end("available");
	  		return;
	  	}
	  	res.end("taken");
    }
}



//index.ts
let register = new Register(db);
app.use(bodyParser.urlencoded({ extended: false }));
app.use(bodyParser.json());
app.use(express.json());
app.post('/checkemailp', register.onPostCheckMail);