transfer a value to boolean

[MAYDAY1993]

I'm wondering why using !! is best and Boolean() is good but new Boolean is bad,can you provide some references or some pratice to help me understand this rule? I know that using new Boolean can new an object and we can other methods to this object ,etc.Thank you for answering
https://github.com/airbnb/javascript#coercion--booleans

[ljharb]

Sure!

new Boolean() produces an object - as opposed to a boolean primitive. This is a holdover from Java patterns, and should always be avoided, as there's not really any use case to use so-called "boxed primitives" - ie, object versions of a primitive.

Boolean(x) and !!x are equivalent except that !! is syntax, and as such, can't ever be broken by somebody replacing the global Boolean. Separately, !! is a common idiom for "cast to boolean" in many programming languages, so it's easy to understand.

[MAYDAY1993]

@ljharb got it, !! and Boolean's rule is the same,right?That means using !! is simplier ,I will use !! for casting to boolean