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JavaScript Programmer’s Reference Property JavaScript JScript N IE Opera DOM HTML Notes accept 5.0 + 5.0 + Warning accessKey 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning alt 3.0 + 4.0 + - dataFld 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning dataFormatAs 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning dataSrc 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning form 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning name 1.5 + 3.0 + 6.0 + 4.0 + 1 + - status 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning tabIndex 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning type 1.5 + 3.0 + 6.0 + 4.0 + -1 + -ReadOnly value 1.5 + 3.0 + 6.0 + 4.0 + -1 + Warning Method JavaScript JScript N IE Opera DOM HTML Notes createTextRange() 1.5 + 3.0 + 6.0 + 4.0 + 1 + Warning Event name JavaScript JScript N IE Opera DOM HTML Notes onAfterUpdate 3.0 + 4.0 + - onBeforeUpdate 3.0 + 4.0 + - onBlur 1.5 + 3.0 + 6.0 + 4.0 + -Warning onClick 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onDblClick 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onDragStart 3.0 + 4.0 + - onFilterChange 3.0 + 4.0 + - onFocus 1.5 + 3.0 + 6.0 + 4.0 + -Warning onHelp 3.0 + 4.0 + Warning onKeyDown 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onKeyPress 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onKeyUp 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onMouseDown 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onMouseMove 1.5 + 3.0 + 6.0 + 4.0 + 4.0 + Warning onMouseOut 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onMouseOver 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onMouseUp 1.5 + 3.0 + 6.0 + 4.0 + -4.0 + Warning onResize 1.5 + 3.0 + 6.0 + 4.0 + Warning onRowEnter 3.0 + 4.0 + - onRowExit 3.0 + 4.0 + - onSelectStart 3.0 + 4.0 + - Inheritance chain: Element object, Node object

B BUTTON object (Object/HTML) BUTTON object (Object/HTML) An object that represents a special MSIE element. Availability: DOM level 1 JavaScript 1.5 JScript 3.0 Internet Explorer 4.0 Netscape 6.0 Inherits from: Element object IE myBUTTON = myDocument.all.anElementID IE myBUTTON = myDocument.all.tags(”BUTTON”) [anIndex] IE myBUTTON = myDocument.all[aName] -myBUTTON = myDocument.getElementById (anElementID) -myBUTTON = myDocument.getElementsByName (aName)[anIndex] JavaScript syntax: -myBUTTON = myDocument.getElementsByTagName (”BUTTON”)[anIndex] HTML syntax: … anIndex A valid reference to an item in the collection aName The NAMEattribute of an element Argument list: anElementID The ID attribute of an element Object properties: accept, accessKey, alt, dataFld, dataFormatAs, dataSrc, form,name, status, tabIndex, type, value Object methods: createTextRange() Event handlers: onAfterUpdate, onBeforeUpdate, onBlur, onClick, onDblClick, onDragStart, onFilterChange, onFocus, onHelp, onKeyDown, onKeyPress, onKeyUp, onMouseDown, onMouseMove, onMouseOut, onMouseOver, onMouseUp, onResize,onRowEnter, onRowExit,onSelectStart This is an additional kind of button object, over and above that provided for the tag. Warnings: . This object is not the same as a Button object, which is a convenience class that is really instantiated as an Input object. Netscape only supports Button (Input) objects and does not support BUTTON objects. MSIE supports both. The properties of each type of button object are different. Element object, Element.isTextEdit, Form.elements[], FormElement object,Input object, Input.accessKey, onClick,TextRange object See also:

JavaScript Programmer’s Reference Button.type (Property) The type value for the object. Availability: DOM level 1 JavaScript 1.1 JScript 1.0 Internet Explorer 3.02 Netscape 3.0 Opera 3.0 Property/method value type: String primitive JavaScript syntax: -myButton.type HTML syntax: The value of this property will be “button” when the HTML tag describes a form Button object. See also: Input.type Property attributes: ReadOnly. Button.value (Property) The text string displayed in the button. Availability: DOM level 1 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Opera 3.0 Property/method value type: String primitive JavaScript syntax: -myButton.value The value of a button is also used to place a legend into the button image on screen. Warnings: . This property may be changed on some platforms, but not others. See also: Input.value

B Button.handleEvent() (Method) Event name JavaScript JScript N IE Opera DOM HTML Notes onKeyDown 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onKeyPress 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onKeyUp 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onMouseDown 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onMouseMove 1.2 + 3.0 + 4.0 + 4.0 + 4.0 + Warning onMouseOut 1.1 + 3.0 + 3.0 + 4.0 + 3.0 + 4.0 + Warning onMouseOver 1.0 + 3.0 + 2.0 + 4.0 + 3.0 + 4.0 + Warning onMouseUp 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onRowEnter 3.0 + 4.0 + - onRowExit 3.0 + 4.0 + - Inheritance chain: Element object, Input object, Node object Button.handleEvent() (Method) Passes an event to the appropriate handler for this object. Availability: JavaScript 1.2 Netscape 4.0 Property/method value type: undefined JavaScript syntax: N myResetButton.handleEvent (anEvent) Argument list: anEvent An event to be handled by this object This applies to Netscape prior to version 6.0. From that release onwards, event management follows the guidelines in the DOM level 3 event specification. On receipt of a call to this method, the receiving object will look at its available set of event handler functions and pass the event to an appropriately mapped handler function. It is essentially an event dispatcher that is granular down to the object level. The argument value is an Eventobject that contains information about the event. See also: handleEvent()

JavaScript Programmer’s Reference Many properties, methods and event handlers for this object are inherited from the Input object class. Refer to topics grouped with the “Input” prefix for details of common functionality across all sub-classes of the Input object super-class. There isn’t really a Button object class in Netscape, but it is helpful when trying to understand the wide variety of input element types if we can reduce the complexity by discussing only the properties and methods of a button. In actual fact, the object is represented as an item of the Input object class. In MSIE, there is a special BUTTON class that is used to represent a tag. It is documented separately in its own topics. The Buttonobject is the correct spelling for a DOM level 1 compliant implementation. Event handling support via properties containing function objects was added to Button objects at version 1.1 of JavaScript. Warnings: . Note that on MSIE, Inputobjects are actually INPUT objects, because MSIE follows a general rule of naming object classes after the capitalized name of the HTML tag that instantiates them. However, in some special cases, MSIE creates other object types. For buttons, it uses the BUTTON class. . Netscape does not support the defaultValue property for this sub-class of the Input object. See also: Property JavaScript JScript N IE Opera DOM HTML Notes type 1.1 + 1.0 + 3.0 + 3.02 + 3.0 + 1 + -ReadOnly value 1.0 + 1.0 + 2.0 + 3.02 + 3.0 + 1 + Warning Method JavaScript JScript N IE Opera DOM HTML Notes handleEvent() 1.2 + 4.0 + - Event name JavaScript JScript N IE Opera DOM HTML Notes onAfterUpdate 3.0 + 4.0 + - onBeforeUpdate 3.0 + 4.0 + - onBlur 1.1 + 3.0 + 3.0 + 4.0 + 3.0 + Warning onClick 1.0 + 3.0 + 2.0 + 4.0 + 3.0 + 4.0 + Warning onDblClick 1.2 + 3.0 + 4.0 + 4.0 + 3.0 + 4.0 + Warning onErrorUpdate 3.0 + 4.0 + - onFilterChange 3.0 + 4.0 + - onFocus 1.0 + 3.0 + 2.0 + 4.0 + 3.0 + Warning onHelp 3.0 + 4.0 + Warning Element object, Element.isTextEdit, Form.elements[], FormElement object, Input object, Input.accessKey, onClick, TextRange object

B Button object (Object/DOM) Cross-references: ECMA 262 edition 2 section 4.3.7 ECMA 262 edition 3 section 4.3.7 Button object (Object/DOM) An object representing an ; HTML button in a form. Availability: DOM level 1 JavaScript 1.0 JScript 1.0 Internet Explorer 3.02 Netscape 2.0 Opera 3.0 Inherits from: Input object -myButton = myDocument.aFormName.anElementName -myButton = myDocument.aFormName.elements [anItemIndex] IE myButton = myDocument.all.anElementID IE myButton = myDocument.all.tags(”INPUT”) [anIndex] IE myButton = myDocument.all[aName] -myButton = myDocument.forms[aFormIndex]. anElementName -myButton = myDocument.forms[aFormIndex]. elements[anItemIndex] -myButton = myDocument.getElementById (anElementID) -myButton = myDocument.getElementsByName (aName)[anIndex] JavaScript syntax: -myButton = myDocument.getElementsByTagName (”INPUT”)[anIndex] HTML syntax: anItemIndex A valid reference to an item in the collection aName The nameattribute of an element anElementID The ID attribute of an element aFormIndex A reference to a single form in the forms collection Argument list: anIndex A valid reference to an item in the collection Object properties: type, value Object methods: handleEvent() Event handlers: onAfterUpdate, onBeforeUpdate,onBlur, onClick, onDblClick, onErrorUpdate, onFilterChange, onFocus,onHelp, onKeyDown, onKeyPress, onKeyUp, onMouseDown, onMouseMove, onMouseOut, onMouseOver, onMouseUp, onRowEnter, onRowExit

JavaScript Programmer’s Reference Examples of built-in functions are parseInt()and Math.exp(). These are functions provided by the Global object and the Math object respectively. They may be referred to as built-in methods in some documentation. None of the built-in functions implement the internal Construct() method and therefore they cannot be used with the new operator to create another instantiation. Generally, none of the built-in functions will have a prototype property, but since they cannot be instantiated this should not cause any problems. Built-in function objects have a length property whose value is an integer. This generally indicates the number of arguments the function expects to be supplied with. Sometimes functions may be supplied with optional arguments. The length value returns the maximum number of arguments that are expected. The length property of a built-in function has the ReadOnly, DontDelete and DontEnum attributes set for it. Generally, all the other properties of a built-in function have the DontEnum attribute set. See also: Function object,Native object Cross-references: ECMA 262 edition 2 section 15 ECMA 262 edition 3 section 15 Built-in method (Definition) Object methods that are provided as part of the base JavaScript implementation. Refer to: Built-in function Built-in object (Definition) Objects that are part of the core JavaScript implementation. Availability: ECMAScript edition 2 A built-in object is provided by the core interpreter independently of the host environment. Built-in objects are available at the outset of script execution and do not need to be created. They are all native objects. Additional built-in objects may be added by the implementation over and above those specified by the core functionality in the language specification. See also: Native object

B btoa() (Method) Whether it will do this is open to question as it could detract from its dominance of the operating system marketplace. This conflict of interests is potentially damaging for the end-user and the web developer. Right at this moment, there is a significant proportion of the feature set in MSIE that is not supported on platforms other than Windows. Granted, it is acceptable that COM and ActiveX cannot easily be provided on non-Windows platforms, but the CSS support should be identical, as should the integration with clipboards and other parts of the OS where it is possible. Netscape 6.0 has just been released in its final form as this is being written. The new version is so radically different as to classify it as being a different browser. Its internal document model follows the DOM specification very closely. Netscape had adhered to the DOM specified class names where Microsoft has not, even though it has constructed a DOM representative object model in the browser. Maybe Netscape can win back some proportion of the users it has lost to Microsoft in the last few years. However, there is still much to be done to correct some shortcomings in the released quality of the new Netscape browser. btoa() (Method) Used to encode some data into base-64 form. JavaScript 1.2 Availability: Netscape 4.0 Property/method value type: String primitive JavaScript syntax: Argument list: N btoa(aBinaryString) N myWindow.btoa(aBinaryString) aBinaryString A string of binary data to be encoded See also: Window.atob(), Window.btoa() Built-in function (Definition) Functions that are part of the core JavaScript implementation. Availability: ECMAScript edition 2 Built-in functions are implemented as Function objects.

JavaScript Programmer’s Reference Downwards compatibility, where code using features in a later browser does not cause errors in an earlier browser, is a little more difficult to provide. HTML has good downwards compatibility due mainly to the fact that if a tag is unrecognized, it is simply ignored. That means web pages containing new features simply display any contained text inside the unrecognized block as if the unsupported tag did not exist. This may be easy to manage with HTML, but is not feasible with a scripting language because you can’t expect the browser simply not to execute a line of script. However, you can code defensively in such a way that your scripts may be downwards compatible. To code defensively means to check for the existence of a feature before using it, and also to check that objects are defined before trying to modify their properties. You can check the version of the browser and switch various features of your scripts on and off accordingly. With a little thought and planning, you can design your script so that it degrades graceful if it is run on less capable browser versions than that for which you originally designed it. The differences between browsers are now so complex and so diverse that it is difficult to encompass them all in a single reference source. This book is structured to allow it to be revised on a component-by-component basis so that where browsers differ from one another, the granularity of the book is approximately the same and can track those differences as they become known. The differences between the browsers may change in very subtle ways even with minor browser version changes. We concentrate on the differences between major versions and use annotations to cover important differences between minor browser versions. Any feedback or observations you care to submit will be welcomed, tested, and added to the future editions of the book. Good workaround techniques involve innovative use of scripts to create your own properties and methods to emulate missing functionality. For example, the window.opener property is not available on all versions of Netscape. You could create a property of your own that refers to the parent window when a new window object is created. If that property is always present and created under script control, then you can use that property rather than the one that may or may not be present in the built-in object model. This is generally more robust, but may not exploit the very latest features of the available browsers. See also: Compatibility, Date object, Defensive coding, Internet Explorer, Window.opener Browser wars (Definition) The contest between browser manufacturers to gain dominance in the market. As this is being written, it is clear that Microsoft has won the war of the browsers for now at least. The Netscape browser has lost market share, to the extent that it is fast becoming a minority browser. This poses an interesting situation, in that Microsoft has sufficient market share that it can perhaps reduce the effort that it puts into browser support. Actually, it is at such a time that it should put even more resources into it. That is because, now that it is so dominant, it should be obliged to make sure its browser is supported identically on every platform it is available on, and make it available on any remaining platforms.

B Browser version compatibility (Advice) Browser version compatibility (Advice) Browser upgrades are not always upwardly compatible. It is fairly obvious that as browsers are improved, new features will be added. This suggests that you might upgrade and begin to exploit those new features. At the next browser upgrade, these features should still be available, while yet more are introduced. This is called upwards compatibility. This is generally no problem.