Javascript Reserved Words

JavaScript has a number of reserved keywords. These are the words that we cannot use as identifiers (variable names, function names, and loop labels) in our JavaScript programs.


Reserved keywords in ECMAScript 5

The following list shows the keywords that are reserved in ECMAScript 5 and also includes keywords that are reserved for future as well as keywords that are disallowed in strict mode:-

argumentsEnuminstanceof
breakEvalinterface
caseExportlet
catchExtendsnew
classFalsenull
constfinallypackage
continueForprivate
debuggerfunctionprotected
defaultIfpublic
deleteImplementsReturn
doimportstatic
elseInsuper

Reserved keywords in ECMAScript 6

The following list shows the keywords that are reserved in ECMAScript 6 and also includes keywords that are reserved for future as well as keywords that are disallowed in strict mode.

argumentselsein
awaitEnuminstanceof
breakevalinterface
caseexportlet
catchextendsnew
classfalsenull
constfinallypackage
continueforprivate
debuggerfunctionprotected
defaultifpublic
deleteimplementsreturn
doimportstatic

Future Reserved keywords in Older Standards

The following list shows the keywords that were reserved as future keywords by the older specifications (before ECMAScript 5 or ES5).

abstractint
booleanlong
bytenative
charshort
doublesynchronized
finalthrows
floattransient
gotovolatile