Wednesday, April 25, 2018

JavaScript Reserved Words


JavaScript Reserved Words

In JavaScript you cannot use these reserved words as variables, labels, or function names:
abstract   arguments    await*      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
Words marked with* are new in ECMAScript 5 and 6.
You can read more about the different JavaScript versions in the chapter JS Versions.

Removed Reserved Words
The following reserved words has been removed from the ECMAScript 5/6 standard:
abstract   boolean   byte    char
double     final    float   goto
int long    native short
synchronized     throws     transient volatile
Do not use these words as variables. ECMAScript 5/6 does not have full support in all browsers.

JavaScript Objects, Properties, and Methods
You should also avoid using the name of JavaScript built-in objects, properties, and methods:
Array  Date   eval    function
hasOwnProperty     Infinity     isFinite     isNaN
isPrototypeOf    length Math  NaN
name Number   Object      prototype
String toString   undefined     valueOf
Java Reserved Words
JavaScript is often used together with Java. You should avoid using some Java objects and properties as JavaScript identifiers:
getClass   java    JavaArray      javaClass
JavaObject    JavaPackage      
Other Reserved Words
JavaScript can be used as the programming language in many applications.

You should also avoid using the name of HTML and Window objects and properties:
alert   all  anchor     anchors
area    assign blur     button
checkbox clearInterval clearTimeout      clientInformation
close   closed      confirm   constructor
crypto      decodeURI    decodeURIComponent      defaultStatus
document     element   elements embed
embeds   encodeURI    encodeURIComponent      escape
event  fileUpload     focus  form
forms frame innerHeight  innerWidth
layer   layers link      location
mimeTypes   navigate  navigator frames
frameRate    hidden     history     image
images     offscreenBuffering  open   opener
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
textarea  top      unescape untaint
window              
HTML Event Handlers
In addition you should avoid using the name of all HTML event handlers.

Examples:
onblur      onclick     onerror    onfocus
onkeydown  onkeypress   onkeyup  onmouseover
onload     onmouseup  onmousedown  onsubmit


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