JavaScript devs, what questions do you ask or been asked during interviews?

Questions regarding scope and 'this', most of the time. Asynchronous program flow, quite often (e.g. running multiple sync operations in parallel vs in series). Prototypical inheritance, rarely.

When applying for a position that explicitly mentions ES6, 'var/let/const' and 'implicit this in arrow functions', promises.

When applying for a job that use a specific framework, like "Senior Angular developer", knowing that framework from practice (not tutorials alone) is a must.

What if users dont hace JavaScript activated on browser?

- Warmup: difference between '==' and '==='.

- Warmup: 'arr' is an array declared like this: 'var arr = [1,2,3,4]'. What is the difference between 'arr = []' and 'arr.length = 0'?

- What is 'this'?

- What is a prototype? Give me an example

- What does the 'new' keyword do? What's the difference between 'func()' and 'new func()'?

- How do you do inheritance in a prototyped language like JavaScript?

- How do you parse JSON in JavaScript? Do you use eval()? Why/why not?

- Why do people wrap their code into one big function?

- Do we have exceptions in JavaScript? How do we handle errors?

- Tell me about a feature of ES6 that you like.

In general, I tend to give a lot of importance to scoping, the prototype chain, how types are created and instantiated, and so on.

My favourite question is to write code for prototype based inheritance in vanilla JS. Most of angular guys gets filtered out.

I particularly hate when I get candidates who says they know angular 1/2/4, but no idea how JS works.