A collection of tricky JS interview questions
Implement a polyfill for Promises in the browser which works for ie8
Okay, so not knowing this question is totally fine. It does not make you a bad developer. More over most of the times if you are asking to implement something like this, you'd probably copy something from Stack overflow or some blog site on Google. I realise people may get intimidated by core JS questions during interviews, and not knowing some of it at that moment isn't a testament to how you are . Nevertheless a company's bench mark are such questions.
The questions have an editor button, which will open a VS code editor, and let you try out a few questions.