𝗗𝗼𝘂𝗯𝗹𝗲 𝗡𝗲𝗴𝗮𝘁𝗶𝗼𝗻 (!!)

Have you ever come across the !! or "not not" operator?
Well, I encountered it this morning.

In hashtag #JavaScript, using the double negation (!!) in front of a value or expression is a shorthand technique to convert a value into its boolean equivalent.

const falsyValue = NaN;
const truthyValue = 'JavaScript';

! means NOT.

• The first ! (not) operator converts a value into a Boolean and reverses it, changing truthy values to false and falsy values (e.g., false, 0, null, undefined, NaN, or an empty string) to true.

!falsyValue; // true
!truthyValue // false

• The second ! operator negates the result of the first !operation, converting the value back to its original boolean representation. If the original value is truthy, it remains true after the double negation, and if it is falsy, it becomes false.

!!falsyValue; // false
!!truthyValue // true

Comments

[Cezary Tomczyk]

Sharing article related to stop using double exclamation.

[Tonny Kirwa]

Great... It's a worthy tip

[Afia]

Thank you 😃