One can learn facts. In fact, it is incredibly trivial to do so if you are smart. I need to do it dozens of times a day to do my job, as does any programmer.
I don't program javascript at all, but am vaguely aware of the terrible implicit conversions it does. Isn't that the important part? I do not have memorized that
Why would I (I had to google that, took 5 seconds, btw)? It is ugly, terrible code. Sure, if I spend my days in a terrible code base I might be forced to learn those conversion rules, but that isn't exactly the mark of a hirable person - it is just the employment history of that person.
Now, if somebody who claimed they knew javascript was writing 'j := 0' for assignment I'd be concerned - but probably they've just been writing a lot of Go lately.
I can see a question like this being asked as part of a lead in to a more general discussion about types, type conversion, how different languages manage it and the trade offs thereof. But, most of the nit-picky questions I have ever been asked in an interview were just nit-picky. What is the output of the obfuscated C? What happens if you abuse the syntax like so? Just pointless questions compared to the real thing you should be measuring - can I produce high quality code on schedule and budget that adds value to the organization without making everyone around me wish they were dead rather than talk to me again? Can I recognize inefficieces in the company and improve things? Can I step up and lead a team or a project? If asked to do something outside of my comfort zone, like go on a sales call, can I do it? Will I complain bitterly if asked to fix bugs for awhile? Will I skip off to a new job just as I start becoming productive at your company? Can I mentor junior people? Can I converse with the CEO and tell him difficult facts if necessary? Can others read my code, modify and extend it without undue problems? Can I untangle other people's spaghetti code?
Measure that stuff, not whether I know if 0 == 'false'.
Um, no. If you don't understand types in js, you don't understand js. I'm not hiring a front-end engineer who somehow hasn't learn js unless he or she is a totally raw intern. And a 1st or 2nd year intern, not a 4th. For anyone else, you need to know js, and if you don't understand types, you don't know js. If you need to google your example, you simply can't write js on a daily basis. (The one exception is, as noted below, saying "don't do that, here's why, do this instead"; that's a great answer.)
Types, functions, objects, classes, type conversions, etc, are part of the minimal working set needed to write code in a language.
I don't program javascript at all, but am vaguely aware of the terrible implicit conversions it does. Isn't that the important part? I do not have memorized that
Why would I (I had to google that, took 5 seconds, btw)? It is ugly, terrible code. Sure, if I spend my days in a terrible code base I might be forced to learn those conversion rules, but that isn't exactly the mark of a hirable person - it is just the employment history of that person.Now, if somebody who claimed they knew javascript was writing 'j := 0' for assignment I'd be concerned - but probably they've just been writing a lot of Go lately.
I can see a question like this being asked as part of a lead in to a more general discussion about types, type conversion, how different languages manage it and the trade offs thereof. But, most of the nit-picky questions I have ever been asked in an interview were just nit-picky. What is the output of the obfuscated C? What happens if you abuse the syntax like so? Just pointless questions compared to the real thing you should be measuring - can I produce high quality code on schedule and budget that adds value to the organization without making everyone around me wish they were dead rather than talk to me again? Can I recognize inefficieces in the company and improve things? Can I step up and lead a team or a project? If asked to do something outside of my comfort zone, like go on a sales call, can I do it? Will I complain bitterly if asked to fix bugs for awhile? Will I skip off to a new job just as I start becoming productive at your company? Can I mentor junior people? Can I converse with the CEO and tell him difficult facts if necessary? Can others read my code, modify and extend it without undue problems? Can I untangle other people's spaghetti code?
Measure that stuff, not whether I know if 0 == 'false'.