I'm just curious what kind of in depth, JavaScript specific questions you've seen before or asked candidates. I'm working up the courage to apply for senior roles, but I'm terrified of looking stupid not knowing about XYZ technical thing that 99% of devs don't know.
Ask HN: “Expert Level” JavaScript questions?
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Re: Ask HN: “Expert Level” JavaScript questions?
#2trickiest/deepest questions ive ever gotten are:
variable hoisting
how to extend a class/prototype
es6 features
typescript/flow
tdd
tooling/webpack
Re: Ask HN: “Expert Level” JavaScript questions?
#3Reimplement things from scratch. I’d recommend implementing Promises from scratch as well as several Async [0] functions like auto or series. Both are questions I’ve asked of senior level JS/Node engineers. This isn’t exhaustive but it’s good practice for sure. Good luck!
Re: Ask HN: “Expert Level” JavaScript questions?
#4Interview questions for senior roles won't (or at least shouldn't) be about language specifics but instead about managing a team, distributing technical work, managing timelines etc. Needless to say, depending on the company, ymmv.
Re: Ask HN: “Expert Level” JavaScript questions?
#5There are some weird corners of JavaScript that I went years without knowing. Did you know object literals support getter and setter methods[1]?
As other commenters will point out, such quirks are as easy to look up as they are irrelevant to actual software development.
[1] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guid... "Defining getters and setters"
Re: Ask HN: “Expert Level” JavaScript questions?
#6Senior level JavaScript I would imagine it to be entirely about frameworks and ES6 shims a.k.a. things you don't actually need. I recommend using as many buzz words as possible.
Re: Ask HN: “Expert Level” JavaScript questions?
#7Explain why ['1','1','1'].map(parseInt) returns [1, NaN, 1] but ['1','1','1'].map(n => parseInt(n)) returns [1, 1, 1].
Re: Ask HN: “Expert Level” JavaScript questions?
#8A good interviewer will start at a high level and drill down into what you're experienced with, rather than pick an obscure topic and assume you've done your homework.
For example, they might ask for a hard problem you've recently solved in your last company.
If you say something related to code splitting, you can expect he'll drill down more specifically into webpack, dependency cycles, etc.
If you say something related to frameworks, you'll get questions asking you to back up the choices you've made. Was it mainly developer productivity or performance you optimized? If you say performance, how did you measure? What metrics are you logging?
...
You should prepare by just reviewing hard problems you've done and brushing up on aspects of it you might've forgotten or remind yourself what was difficult about it.
This applies to the coding portion of your interview as well. If you write "===", you should be able to answer what that's for. If you use ".bind(this)", you should know why you had to bind it. For this portion, you can prepare by looking at code you've written and trying to pick out those parts which you never bothered to figure out but always "just did" (e.g. for many people, the === is just something they do because they see it everywhere).
Re: Ask HN: “Expert Level” JavaScript questions?
#9A good interviewer will start at a high level and drill down into what you're experienced with, rather than pick an obscure topic and assume you've done your homework. For example, they might ask for a hard problem you've recently solved in your last company. If you say something related to code splitting, you can expect he'll drill down more specifically into webpack, dependency cycles, etc. If you say something rel…
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Re: Ask HN: “Expert Level” JavaScript questions?
#10Explain why ['1','1','1'].map(parseInt) returns [1, NaN, 1] but ['1','1','1'].map(n => parseInt(n)) returns [1, 1, 1].
What the hell, who on earth thought that behaviour would be a good idea?