KEYWORDS AND RESERVED WORDS

break do instanceof typeof
case else new var
catch finally return void
continue for switch while
debugger* function this with
default if throw
delete in try

 The following is the complete list of reserved words
abstract enum int short
boolean export interface static
byte extends long super
char final native synchronized
class float package throws
const goto private transient
debugger implements protected volatile
double import public

The fifth edition shrinks down the list of reserved words when running in nonstrict mode to the following:
class enum extends super
const export import

When running in strict mode, the fifth edition also places reserved word restrictions on the following:
implements package public
interface private static
let protected yield