It's a handy way to convert any value to a Boolean. If window.chrome is defined and done non-empty value, double negation turns it into just true.

[–] Faresh@lemmy.ml 6 points 9 months ago (2 children)

I've been wondering why not window.chrome == true or Boolean(window.chrome), but it turns out that the former doesn't work and that == has essentially no use unless you remember some completely arbitrary rules, and that JS developers would complain that the latter is too long given the fact that I've seen javascript code using !0 for true and !1 for false, instead of just true and false because they can save 2 to 3 characters that way.

[–] marcos@lemmy.world 6 points 9 months ago

== has essentially no use unless you remember some completely arbitrary rules

If you make sure the types match, like by explicitly converting things on the same line on that example, then you can use it just like if it was ===.

In fact, there are people that defend that if your code behaves differently when you switch those two operators, your code is wrong. (Personally, I defend that JS it a pile of dogshit, and you should avoid going to dig there.)

[–] ivn@jlai.lu 5 points 9 months ago (1 children)

I've never seen the !0 and !1, it is dumb and indicates either young or terrible devs.

Boolean(window.chrome) is the best, !!window.chrome is good, no need to test if it's equal to true if you make it a boolean beforehand.

[–] RedStrider@lemmy.world 1 points 8 months ago

i just added the === true for clarity

[–] CorvidCawder@sh.itjust.works 5 points 9 months ago

JS "idiomatic" way to cast to boolean. But could just be written as !window.chrome instead.