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Cover image for JavaScript Interview Question #38: Can you add multiple arrays in JavaScript?

JavaScript Interview Question #38: Can you add multiple arrays in JavaScript?

coderslang profile image Coderslang: Become a Software Engineer Originally published at learn.coderslang.com on ・1 min read

js-test-38

Can you add multiple arrays in JavaScript? What’s the output?

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The function add(x, y, z) applies the + operator to the provided arguments. Or, simply put, adds them up.

In line 5 we provide it with 3 arrays.

Whenever you try to add arrays in JavaScript, they will be first converted to strings. Every element is separated from the next one by a comma and a single space. In our case:

  • 1, 2
  • 3, 4
  • 5, 6

Then these strings are concatenated, or “glued” together to make a result.


ANSWER: a string 1, 23, 45, 6 will be printed to the console.

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Discussion (8)

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anthager profile image
Anton

Ha! Always fun to see these things! But just as a heads up to people looking through this thread looking for advise for what to study before their interviews, stuff like this is not asked in interviews (atleast not in my experience) but there is a point of knowing that js sometimes does unexpected conversions. Just knowing that and answering "Im not sure but unexpected conversions might happen so I would try it out in the console" should be enough

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alphavader profile image
KB

This 100%

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coderslang profile image
Coderslang: Become a Software Engineer Author

Questions like this can tell the depth of the candidate's knowledge. I've seen "senior" devs completely fail and get pissed off with these "junior" questions.

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anthager profile image
Anton

That says something about their character and I definitely wouldnt want someone with that attitude in my team. But i could see why someone who would consider themselves senior getting frustrated when only asked trivia style questions and if an answer like "there might be fishy stuff going on here so I would just look it up" is not being accepted. Being senior is not having everything memorised, at least not in my book. But getting pissed of looks very bad indeed

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lucassperez profile image
Lucas Perez

This is one of those wtfjs moments

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coderslang profile image
Coderslang: Become a Software Engineer Author

Eventually, we all get used to it :)

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polyterative profile image
Vlady • Edited

this doesn't work on arrays of objects right?

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coderslang profile image
Coderslang: Become a Software Engineer Author

Arrays of objects will behave similarly and be converted to strings as well.

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