Tutorial Appendices

Tutorial 15 - User-Defined Objects

The JavaScript tutorial appendix is a synopsis of important objects, methods, properties, functions ,events and reserved words. It includes a brief history of the JavaScript language.The terms used will help you access an appropriate reference book that explains in detail what the term means. Some useful references are:

JavaScript Reserved Words

Reserved words are words with a special purpose. These words cannot be used as variable names.

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

To avoid unnecessary debugging problems do not use any property or method name as a variable name. Also avoid using a case variant even when it is legal (eg. do not use instanceOf).

Client-Side Objects, Methods & Properties

Client-side objects are basic objects tied to a particular browser. This may cause some inconsistencies in syntax or use as browser versions change. Be aware that differences exist and always test your code. The client-side objects are Document, Form, History, Location, Navigator and Window.

• Document Object - Primary Output
  • content properties - anchors[], applets[], embeds[], forms[], images[], links [], plugins[]
  • display properties - alinkColor, bgColor, fgColor, linkColor, vlinkColor
  • information properties - cookie, domain, lastModified, location, mimeTypes, referrer, title, URL
  • methods - open(), write(), writeln()
• Form Objects - Primary Input
  • form properties - name, target, action, method, encoding, elements, length
  • form methods - submit(), reset()
  • input, textarea and select methods - focus(), blur(), select()
  • button, hidden, reset, and submit object properties - name, value, type
  • checkbox properties - name, value, type, checked, default checked
  • password properties - name, value, type, default value
  • radio button properties - name, value, type, checked, default checked, length
  • select properties - name, value, type, length, options, defaultSelected, index, selected, selectedIndex
  • text, textarea properties - name, value, defaultvalue
• History Object - Access the browser's history file
  • properties - length
  • methods - back(), forward(), go()
• Location Object
  • properties - hash, hostname, href, pathname, port, protocol, search
  • methods - reload(), replace()
• Navigator Object - Root of all Objects
  • properties - appCodeName, appName, appVersion, userAgent
  • methods - javaEnabled()
• Window Object
  • contained objects -
    • Screen Object
    • properties - availHeight, availLeft, availTop, availWidth, colorDepth, height, pixelDepth, width
  • properties - defaultStatus, frames, length, name, opener, parent, self, status, top, window
  • methods - alert(), blur(), clearInterval(), clearTimeout(), close(), confirm(), focus(), open(), print(), prompt(), scroll(), setInterval(), setTimeout(), timeoutID()

ECMA Core Objects, Methods & Properties

ECMA is a standards committee which defines specific core objects (or internal constructs) to help a programmer. Some are used to access operating system functions. Others are used to perform data and string manipulations. The ECMA objects are Array, Boolean, Date, Error, Function, Global, Math, Number, Object, RegExp and String

• Array Object
  • properties - constructor, length, prototype
  • methods - concat(), join(), pop(), push(), reverse(), shift(), slice(), sort(), splice(), toLocaleString(), toString(), unshift(), valueOf()
• Boolean Object
  • properties - constructor, prototype
  • methods - toString(), valueOf()
• Date Object
  • properties - constructor, prototype
  • methods - getDate(), getDay(), getFullYear(), getHours(), getMilliseconds(), getMinutes(), getMonth(), getSeconds(), getTime(), getTimeZoneOffset(), getUTCDate(), getUTCDay(), getUTCFullYear(), getUTCHours(), getUTCMilliseconds(), getUTCMinutes(), getUTCMonth(), getUTCSeconds(), getVarDate(), getYear(), parse(), setDate(), setFullYear(), setHours(), setMilliseconds(), setMinutes(), setMonth(), setSeconds(), setTime(), setUTCDate(), setUTCFullYear(), setUTCHours(), setUTCMilliseconds(), setUTCMinutes(), setUTCMonth(), setUTCSeconds(), setUTCTime(), setUTCYear(), setYear(), toLocaleString(), toUTCString(), toString(), UTC(), valueOf()
• Error Object
  • properties - description, number
  • methods -
• Function Object
  • properties - arguments[], caller, constructor, prototype
  • methods - toString(), valueOf()
• Global Object
  • properties - Infinity, NaN, undefined
  • methods - escape(), eval(), isFinite(), isNaN(), parseFloat(), parseInt(), unescape()
• Math Object
  • properties - E, LN10, LN2, LOG10E, LOG2E, PI, SQRT2, SQRT1_2
  • methods - abs(), acos(), asin(), atan(), atan2(), ceil(), cos(), exp(), floor(), log(), max(), min(), pow(), random(), round(), sin(), sqrt(), tan()
• Number Object
  • properties - MAX_VALUE, MIN_VALUE, NaN, NEGATIVE _INFINITY, POSITIVE_INFINITY, constructor, prototype
  • methods - toLocaleString(), toString(), valueOf()
• Object Object
  • properties - constructor, prototype
  • methods - toLocaleString(), toString(), valueOf()
• RegExp Object
  • properties - $1 - $9, index, input, lastIndex, lastMatch, lastParen, leftContext, rightContext
• String Object
  • properties - constructor, length, prototype
  • display methods - anchor(), big(), blink(), bold(), fixed(), fontcolor(), fontsize(), italics(), small(), strike(), sub(), sup()
  • manipulation methods - charAt(), charCodeAt(), concat(), fromCharCode(), indexOf(), lastIndexOf(), link(), match(), replace(), search(), slice(), split(), substr(), substring(), toLowerCase(), toUpperCase(), toString(), valueOf()

JavaScript Events and Event Handlers

JavaScript events are external stimulae or actions by a user or by the operating system that cause internal procedures to run which modify the 'properties' of 'objects'. Clicking the mouse, pressing the [Enter] key, and moving the cursor are some of the 'events' that start the ball rolling. Event handlers are the specific methods for reacting to an event.

System Event Handlers:

User Event Handlers:

NOTE: When used as an attribute, an event handler must be typed in lowercase only (eg. onclick) to meet XHTML specifications! Most, but not all of the following user event handlers can be included as form control attributes.

Built-In Functions

In order to help the programmer, JavaScript includes several useful built-in functions. Their names and usage follows:

with (document) {
   writeln(lastmodified);
   writeln(location);
   writeln(title);
   }

A Brief History of JavaScript

Everything has a history and often knowing that history gives insight into why things are done the way they are and what issued were solved and what were missed or created. This topic attempts to reveal the evolution of JavaScript.

Originally browsers only had one method of interactivity: forms submitted to other sites. What was desperately required was interactivity within the client browser itself. Netscape created a language called LiveScript which was interpreted and provided the required functionality for internal utilities and interaction. LiveScript was rebranded as JavaScript to gain from the good publicity that Java was getting. Its only commonality with Java is that both are OOP languages that use C syntax as a starting point.

Successive versions have added functionality in response to user demand. Image support, arrays, and plug-ins are examples of these additions. MicroSoft implemented its version as JScript but unfortunately often did things differently or included features not implemented in JavaScript. This was part of the browser wars and caused much grief for program authors.

Finally in 1996, developers had had enough and asked for standards! Unfortunately several standards group accepted the challenge. ECMA was the most successful and now ECMAScript is available on most browsers. However, ECMASCript is restricted to defining the core language. The browser interface is standardized through the DOM recommendation of w3.org. DOM also covers other languages that must interface with a browser, not just JavaScript.

Tutorial 15 - User-Defined Objects

Copyright (c) 2005 by John W. M. Russell