Restricting possible user inputs

[flauc]

This isn't really an issue, just a question?

This is how i currently restrict the possible inputs

let a = (yield prompt("Create app? (Y/n) ")) || "Y";
while (!(/^([yn]|(yes)|(no))$/ig.test(a))) a= yield prompt("Create app? (Y/n) ");

Is there a better way of doing it?