What's the difference between double exclamation operator and Boolean() in JavaScript?

Question

I know that !!variable will convert variable into a boolean value and the function Boolean(), according to the ecma262 spec, will also perform a type conversion by calling ToBoolean(value).

My question is: what's the difference? Is !! better in performance than Boolean() ?

@sachleen I think he is referring to parts of the ecma spec. — alex, Dec 21 '12 at 04:37
My total guess is: absolutely no difference, and performance difference is negligible. But someone's gonna come around with some data soon enough. — Matchu, Dec 21 '12 at 04:38

alex · Accepted Answer · 2012-12-21T04:46:39.917

9

They are the same, as the ! operator will call ToBoolean() internally on its operand, and then flip that returned value, while Boolean() will call ToBoolean() internally on its argument.

edited Dec 21 '12 at 04:46

answered Dec 21 '12 at 04:38

alex

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What's the difference between double exclamation operator and Boolean() in JavaScript?

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