Learn JavaScript Reserved Words

the Keywords below are reserved words, You can't use them as identifiers (variables names, function names, and loop labels)

tip: Keywords with* are new in ECMAScript 6 and 5.

double finally goto yield
with protected continue while
void var typeof true
volatile this transient synchronized
boolean catch const final
static short default arguments
throws switch throw super*
try return private package
debugger public await* null
new native long let*
abstract case byte break
class* char delete do
interface int instanceof in
else false extends* float
for export* enum* eval
implements import* function if

Learn about the different JavaScript versions in our Javascript versions course.

Removed Reserved Words

The reserved keywords below have been removed from the ECMAScript 6/5 standard, don't use them:

boolean final double abstract
native long int volatile
goto float short synchronized
byte transient throws char

JavaScript Objects, Methods, and Properties.

Try to avoid the next JavaScript objects, methods, and properties.

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

More Reserved Words

Since Javascript is mostly used with other programming languages, It will be best practice to avoid the next keywords as well:

area assign blur button
close closed confirm constructor
alert all anchor anchors
crypto decodeURI decodeURIComponent defaultStatus
checkbox clearInterval clearTimeout clientInformation
embeds encodeURI encodeURIComponent escape
event fileUpload focus form
document element elements embed
layer layers link location
forms frame innerHeight innerWidth
frameRate hidden history image
images offscreenBuffering open opener
mimeTypes navigate navigator frames
option outerHeight outerWidth packages
pageXOffset pageYOffset parent parseFloat
parseInt password pkcs11 plugin
prompt propertyIsEnum radio reset
screenX screenY scroll secure
select self setInterval setTimeout
status submit taint text
window top unescape untaint

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