Summary of JavaScript reserved keywords_javascript tips

JavaScript Standard

All modern browsers already fully support ES5 (ECMAScript 5).

JavaScript reserved keyword (keyword)

Javascript reserved keywords (identifiers) cannot be used as variable, label or function names. Some reserved keywords are used by Javascript for future extensions.

abstract	arguments	boolean	break	byte
case	catch	char	class*	const
continue	debugger	default	delete	do
double	else	enum*	eval	export*
extends*	false	final	finally	float
for	function	goto	if	implements
import*	in	instanceof	int	interface
let	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	yield

* The keywords marked are newly added in ECMAScript5.

JavaScript objects, properties and methods

You should also avoid using the names of built-in JavaScript objects, properties, and methods as Javascript variable or function names:

Array	Date	eval	function	hasOwnProperty
Infinity	isFinite	isNaN	isPrototypeOf	length
Math	NaN	name	Number	Object
prototype	String	toString	undefined	valueOf

Java reserved keywords

JavaScript is often used together with Java. There are some Java objects and properties that you should avoid using as JavaScript identifiers:

getClass

java

JavaArray

javaClass

JavaObject

JavaPackage

Windows reserved word

JavaScript can be used outside of HTML. It can be used as a programming language in many other applications.
In HTML, you must (and for the sake of portability, you should) avoid using the names of HTML and Windows objects and properties as Javascript variable and function names:

alert	all	anchor	anchors	area
assign	blur	button	checkbox	clearInterval
clearTimeout	clientInformation	close	closed	confirm
constructor	crypto