What is the !! (not not) operator in JavaScript?

Converts Object to boolean. If it was falsey (e.g. 0, null, undefined, etc.), it will be false, otherwise, true.

!oObject  // inverted boolean
!!oObject // non inverted boolean so true boolean 

Representation

So !! is not an operator, it's just the ! operator twice.

Example :

<CustomModal
  disabled={isDisable}
  title="Delete"
  children="Are you sure you want to delete ?"
  onCancel={() => setDataToDelete(null)}
  onConfirm={() => {}}
  show={!!dataToDelete} //show only accepts boolean
/>;

Comments

[juanmillord]

So its a good way to do something only when what you are evaluating is true. Thank you.

[Jose Torreblanca]

Boolean(dataToDelete)