JavaScript Pocket Reference

The JavaScript Language

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break do if switch typeof

case else in this var

catch false instanceof throw void

continue finally new true while

default for null try with

delete function return

JavaScript also reserves the following words for possible

future extensions. You may not use any of these words as

identifiers either:

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

In addition, you should avoid creating variables that have the

same name as global properties and methods: see the Glo-

bal, Object, and Window reference pages. Within functions,

do not use the identifier

arguments as an argument name or

local variable name.

Variables

Variables are declared and initialized with the var statement:

var i = 1+2+3;

var x = 3, message = 'hello world';

Variable declarations in top-level JavaScript code may be

omitted, but they are required to declare local variables

within the body of a function.

JavaScript variables are untyped: they can contain values of

any data type.

Global variables in JavaScript are implemented as properties

of a special Global object. Local variables within functions

are implemented as properties of the Argument object for