Reserved Words

Various words and symbols are reserved by JavaScript. These words cannot be used as variable names, nor can the symbols be used within them. They are listed in the following table.

abstract	Boolean	break
byte	Case	catch
char	Class	const
continue	Debugger	default
delete	Do	double
else	Enum	export
extends	False	final
finally	Float	for
function	Goto	if
implements	Import	in
instanceof	Int	interface
long	Native	new
null	Package	private
protected	Public	return
short	Static	super
switch	synchronized	this
throw	Throws	transient
true	Try	typeof
var	Void	volatile
while	With
-	!	~
%	/	*
>	<	=
&	^	\|
+	?

Other Identifiers to Avoid

It is best to avoid the use of the following identifiers as variable names.

JavaScript 1.0

abs acos anchor asin atan atan2 big blink bold ceil charAt comment cos Date E escape eval exp fixed floor fontcolor fontsize getDate getDay getHours getMinutes getMonth getSeconds getTime getTimezoneOffset getYear indexOf isNaN italics lastIndexOf link log LOG10E LOG2E LN10 LN2 Math max min Object parse parseFloat parseInt PI pow random round setDate setHours setMinutes setMonth setSeconds setTime setYear sin slice small sqrt SQRT1_2 SQRT2 strike String sub substr substring sup tan toGMTString toLocaleString toLowerCase toUpperCase unescape UTC

JavaScript 1.1

caller className constructor java JavaArray JavaClass JavaObject JavaPackage join length MAX_VALUE MIN_VALUE NaN NEGATIVE_INFINITY netscape Number POSITIVE_INFINITY prototype reverse sort split sun toString valueOf

JavaScript 1.2

arity callee charCodeAt compile concat exec fromCharCode global ignoreCase index input label lastIndex lastMatch lastParen leftContext match multiline Number Packages pop push RegExp replace rightContext search shift slice splice source String test unshift unwatch watch

JavaScript 1.3

apply call getFullYear getMilliseconds getUTCDate getUTCDay getUTCFullYear getUTCHours getUTCMilliseconds getUTCMinutes getUTCMonth getUTCSeconds Infinity isFinite NaN setFullYear setMilliseconds setUTCDate setUTCFullYear setUTCHours setUTCMilliseconds setUTCMinutes setUTCMonth setUTCSeconds toSource toUTCString undefined