Is there an interest to use double boolean negation?

Question

As a beginner in Javascript, I have a question which may seem a bit weird. I am using an external lib I found on the web in which I found the code below :

if('useHoles' in c){
   this.config.useHoles = !!c.useHoles;
}

Is there an interest to use the double exclamation mark or is it just some clumsy code ?

Couldn't find any answer yet so I guess I can just remove them but I wanted to be 100% sure.

Possible duplicate of [When to use the double not (!!) operator in JavaScript](https://stackoverflow.com/questions/2174297/when-to-use-the-double-not-operator-in-javascript) — Jonas Wilms, Jul 28 '17 at 09:26

score 3 · Accepted Answer · answered Jul 28 '17 at 09:19

3

With the double ! you force an object to return something that is "boolean-able", even if null or something else, that can be evaluated as bool true or false.

answered Jul 28 '17 at 09:19

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Is there an interest to use double boolean negation?

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