This is particularly confusing since many other popular languages don’t do it that way.

Confusingly, this means that the string "false", the string "0", an empty object {}, and an empty array [] are all truthy. You can double check this by passing an object into the Boolean function (e.g. Boolean("0");).
Why ['1', '7', '11'].map(parseInt) returns [1, NaN, 3] in Javascript
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Eric Tong
Tom Ritchford
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1 min read·
Jun 14, 2019
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This is particularly confusing since many other popular languages don’t do it that way. For example, Python goes to some effort to do it right so [], {} and so on are all falsy, and you can customize this for your own classes.
It also seems jarringly weird that NaN is falsy. Intuitively I would want only 0 to be falsy and all other numbers, including inf and NaN, to be truthy.
Good to know all this!
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Written by Tom Ritchford1.5K Followers
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