What are Symbol primitive type in JavaScript?

1.	What are Symbol primitive type in JavaScript?
Answer» null (var null) In JavaScript, null is a RESERVED identifier, therefore we cannot use it as an identifier in JavaScript. An error can be seen if we will write: &LT;html> <body> <script> var null; </script> </body> </html> The following is the error VISIBLE when you will press F12 on browser: SYNTAXERROR: Unexpected token null The web browser throws an error for “var null” since it is a reserved identifier. UNDEFINED (var undefined) The undefined is not a reserved identifier, therefore if you will write the following, then no error would be thrown: <html> <body> <script> var undefined; document.write(undefined); </script> </body> </html> Even if it is undefined, let us see what would be the output: Undefined

Answer»

null (var null)

In JavaScript, null is a RESERVED identifier, therefore we cannot use it as an identifier in JavaScript. An error can be seen if we will write:

&LT;html> <body> <script> var null; </script> </body> </html>

The following is the error VISIBLE when you will press F12 on browser:

SYNTAXERROR: Unexpected token null

The web browser throws an error for “var null” since it is a reserved identifier.

UNDEFINED (var undefined)

The undefined is not a reserved identifier, therefore if you will write the following, then no error would be thrown:

<html> <body> <script> var undefined; document.write(undefined); </script> </body> </html>

Even if it is undefined, let us see what would be the output:

Undefined

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