Front-end developer interview questions

Question

There are a lot of good interview questions (even "puzzles") for software developers here on SO, but I was wondering if anyone had some good questions for a front-end developer position. We're looking for someone who knows HTML+CSS+JS.

Some of the obvious questions:

• Have you worked with javascript libraries? - follow-up: which, and why that one over others?
• Are you following the development of HTML5 and CSS3? - follow-up: Which features are you looking forward to the most, and why?

Do you know any good "puzzles" for a front-end developer? Maybe a JS fizz-buzz?

edit: changed the two questions to be a bit more open.

Answer 1

The questions you propose are too easy to bluff on. "Have you worked with javascript libraries? Yes. JQuery." That doesn't tell you much. I suggest turning the questions a little more like this:

• Describe for me how to write an extension for JQuery.
• Describe the architecture of JQuery and compare it to YUI
• What would you change about HTML5/CSS3 if you could?
• What is your favorite feature in HTML5 and how would you use it?

These get to more of a sense of understanding than mere acknowledgement of facts.

You could simply ask fizz-buzz in Javascript. It couldn't hurt.

Answer 2

It depends on the level you are interviewing for. I recently finished up a good round of interviews for frontend positions (and found a good job! ;), here are some of the questions I was asked which I thought stood out (and were more challenging than others).

• Explain the difference between the JavaScript call and apply functions.

• Puzzle: Emulate the game "Secret Santa" where there are 3 or more participants, no participant can receive their own gift or receive more than one gift. Do this in JavaScript.

• Identify two ways in which you can clear a floated element with HTML/CSS.

• What is the difference between event bubbling and event capture?

• Describe a rendering problem you had in IE6 or IE7, and how you overcame it.

• Define the term 'closure' and give an example of it in JavaScript.

• Explain the differences between the IE and DOM standard event model.

• What is the proper way to evaluate JSON from the server, and why is this the proper way?

Answer 3

What is the best user experience idea you coined and implemented in your past projects ?

Answer 4

I like to ask to "convert" to html a classic paper (ie, journal, magazine, etc.) to a semantically correct markup.

It helps to know if the developer knows about semantics, seo, etc.

Some other questions I like to ask:

• How to explain DOM.
• Why and when should you use div ? (ie, not every time, only when insufficient markup or need to wrap several elements)
• When using IDs, when using classes ?
• Do you use some naming convention for your ids and classes.

Therefor, I like to ask question that helps to find logical persons, not the one who knows about all functions but have a good analysis. I think you must make a difference between skills and experiences.

and most of the question already listed by other people.

Answer 5

• What inspires you to create good looking and functional websites?
• What do you think are the strengths of digital marketing via web and social media?
• Which areas of web development are you interested in? please range from most interested to least interested. (design, code (HTML, CSS), interactivity (Flash, silverlight, jQuery), usability, SEO etc).
• Why is it important to write good semantic code, and separate information(HTML) from layout(CSS) and behaviour (javascript)
• What is a good website for you? feel free to show examples