JScript Reserved Words (Visual Studio - JScript)

JScript has a number of reserved words that have a specific meaning in the JScript language syntax. Consequently, these words are not good choices for names of functions, variables, or constants in scripts. There are three classes of reserved words.

Protected Reserved Words

Protected reserved keywords cannot be used as identifiers. Using a protected reserved word as an identifier causes a compilation error when loading your script.

break	case	catch	class	const
continue	debugger	default	delete	do
else	export	extends	false	finally
for	function	if	import	in
instanceof	new	null	protected	return
super	switch	this	throw	true
try	typeof	var	while	with

Note

Although "export" is a protected reserved word, it has no implementation.

New Reserved Words

JScript also has a list of new reserved words. Like protected reserved words, these keywords have special meaning within the current version of JScript. For backward compatibility reasons, new reserved words can be used as an identifiers. Once a new reserved word is used as an identifier, it loses its meaning as a keyword in the script. Using new reserved words as identifiers can cause confusion and should be avoided.

abstract	boolean	byte	char	decimal
double	enum	final	float	get
implements	int	interface	internal	long
package	private	protected	public	sbyte
set	short	static	uint	ulong
ushort	void

Future Reserved Words

JScript has a list of future reserved words, which are proposed as keywords in future extensions of JScript. Like the new reserved words, these may be used as identifiers in the current version of JScript. However, by avoiding these words, it will be easier to update scripts to take advantage of the features in upcoming versions of JScript.

When choosing identifiers it is also important to avoid words that are already the names of intrinsic JScript objects or functions, such as String or parseInt.

assert	ensure	event	goto	invariant
namespace	native	require	synchronized	throws
transient	use	volatile

See Also

Other Resources

JScript Reference

JScript Language Tour