Logical NOT operator is represented by the exclamatory (!
) symbol. It is a unary operator.
Here is how you use the logical NOT operator in JavaScript.
!x
The ! operator is written before an operand. It returns true
if an operand evaluates to falsy. If an operand is truthy then it returns false
. In simple terms, it returns true
or false
.
In JavaScript, you know null
, undefined
, NaN
, 0, and "" are falsy values. You can verify this by applying the logical NOT operator twice.
console.log(!!null); //false console.log(!!undefined); //false console.log(!!NaN); //false console.log(!!0); //false console.log(!!""); //false