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4

@zupa: what !!a does?

user1094081
– user1094081

2015-04-23 10:59:40 +00:00
Commented Apr 23, 2015 at 10:59
10

@3000 well, if we leave out the (!!a) part it crashes, because null and undefined have no constructors. (!!a) filters them out. Does that answer your question?

zupa
– zupa

2015-04-27 15:26:33 +00:00
Commented Apr 27, 2015 at 15:26
3

@zupa @3000 Boolean(a) is longer, but far more intuitive. Just don't use new Boolean(a): (here's why)!

Jeroen Versteeg
– Jeroen Versteeg

2015-08-20 13:32:48 +00:00
Commented Aug 20, 2015 at 13:32
30

Surprised the best answer is so far down the page. This basically answers the question- would this be represented in JSON as something starting with a { character. For the array case, as long as you don't need to support IE < 9, you can use Array.isArray() to determine if something is an array. It passes all the test cases you provided.

Kip
– Kip

2016-03-10 14:56:08 +00:00
Commented Mar 10, 2016 at 14:56
4

@BradKent Without the double negative !!a isObject(null) would return null instead of false

AKG
– AKG

2019-08-13 22:43:01 +00:00
Commented Aug 13, 2019 at 22:43

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Correct minor typos or mistakes
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create code fences with backticks ` or tildes ~
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like so
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def function(foo):
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```
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