Why do we use the !! (not not) operator in JavaScript?

1.	Why do we use the !! (not not) operator in JavaScript?
Answer» The “undefined” is used to unset a variable in JavaScript. Declare and INITIALIZE a variable: ]var a = 50; Now reassign the variable with undefined SINCE we wish to unset it: a = undefined; The following is an example: <!DOCTYPE html&GT; <html> <body> <script> var a = 50; a = undefined; document.write(a); </script> </body> </html> The output displays undefined: Undefined If you are implicitly declaring the variable without var keyword, then USE the delete to unset a variable: <!DOCTYPE html> <html> <body> <script> a = 10; delete a; </script> </body> </html>

Answer»

The “undefined” is used to unset a variable in JavaScript.

Declare and INITIALIZE a variable:

]var a = 50;

Now reassign the variable with undefined SINCE we wish to unset it:

a = undefined;

The following is an example:

<!DOCTYPE html&GT; <html> <body> <script> var a = 50; a = undefined; document.write(a); </script> </body> </html>

The output displays undefined:

Undefined

If you are implicitly declaring the variable without var keyword, then USE the delete to unset a variable:

<!DOCTYPE html> <html> <body> <script> a = 10; delete a; </script> </body> </html>

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