Web And Email Hosting, Jsp Web Hosting Blog

JavaScript Programmer’s Reference Property JavaScript JScript N IE Opera NES ECMA Notes constructor 1.1 + 3.0 + 3.0 + 4.0 + 2 + - prototype 1.1 + 3.0 + 3.0 + 4.0 + 3.0 + 2.0 + 2 + - Method JavaScript JScript N IE Opera NES ECMA Notes toSource() 1.3 + 4.06 + 3.0 + - toString() 1.1 + 3.0 + 3.0 + 4.0 + 3.0 + 2.0 + 2 + - valueOf() 1.1 + 3.0 + 3.0 + 4.0 + 2 + - Cross-references: ECMA 262 edition 2 section 4.3.15 ECMA 262 edition 2 section 10.1.5 ECMA 262 edition 2 section 15.6 ECMA 262 edition 3 section 4.3.15 ECMA 262 edition 3 section 15.6 Boolean() (Constructor) A Boolean object constructor. Availability: ECMAScript edition 2 JavaScript 1.1 JScript 3.0 Internet Explorer 4.0 Netscape 3.0 Property/method value type: Boolean object -new Boolean() JavaScript syntax: -new Boolean(aValue) Argument list: aValue A value to be converted to a Boolean object. The Boolean() constructor is used to manufacture new instances of the built-in Boolean object. When the Boolean() constructor is called by the newoperator, it initializes a brand new Boolean object instance. The value of the new Booleanobject instance is the same as the Boolean value yielded by the type conversion of the Boolean() constructor’s parameter.

B Boolean object (Object/core) Boolean object (Object/core) An object of the class “Boolean”. Availability: ECMAScript edition 2 JavaScript 1.1 JScript 3.0 Internet Explorer 4.0 Netscape 3.0 Netscape Enterprise Server 2.0 Opera 3.0 -myBoolean = BooleanValue -myBoolean = new Boolean() JavaScript syntax: -myBoolean = new Boolean(aValue) BooleanValue A Boolean value (either true or false) Argument List aValue A value to be converted to a Boolean object. Object properties: constructor, prototype Object methods: toSource(), toString(), valueOf() An instance of the class “Boolean” is created by using the new operator on the Boolean() constructor. The new object adopts the behavior of the built-in Boolean prototype object through the prototype-inheritance mechanisms. All properties and methods of the prototype are available as if they were part of the new instance. A Boolean object is a member of the type Object and is an instance of the built-in Boolean object. Cloning the built-in Boolean object creates Boolean objects. This is done by calling the Boolean()constructor with the newoperator. For example: myBoolean = new Boolean(true); A Booleanobject can be coerced into a Boolean value and can be used anywhere that a Boolean value would be expected. Programmers familiar with object-oriented techniques may be happy to use the Boolean object, while procedural language programmers may prefer to implement the same functionality with a Boolean value instead. This is an example of the flexibility of JavaScript in its ability to accommodate a variety of users from different backgrounds. The prototype for the Boolean prototype object is the Object prototype object. See also: Boolean. prototype, Native object, Object object, unwatch(), watch()

JavaScript Programmer’s Reference Boolean (Type) A native built-in type. Availability: Property/method value type: ECMAScript edition 2 Boolean primitive Any object or expression that yields a result of type Boolean represents a logical entity. Logical entities can only represent the trueor false states. These are useful as flags or conditional switches in your script. Data Type, false, Fundamental data type, true, Type See also: Cross-references: ECMA 262 edition 2 section 4.3.14 ECMA 262 edition 2 section 8.3 ECMA 262 edition 3 section 4.3.14 ECMA 262 edition 3 section 8.3 O’Reilly JavaScript Definitive Guide page 41 Boolean literal (Primitive value) A literal constant whose type is a built-in primitive value. Availability: Property/method value type: ECMAScript edition 2 Boolean primitive Boolean literals specify constant values for the trueand false values used in relational expressions and are the only two values a Boolean primitive or object can resolve to. false, Implicit conversion, Literal, Token, true See also: Cross-references: ECMA 262 edition 2 section 7.7.2 ECMA 262 edition 3 section 7.8.2

B Boolean (Primitive value) Boolean (Primitive value) A built-in primitive value. Availability: Property/method value type: ECMAScript edition 2 Boolean primitive A Boolean value is a member of the Boolean type and may have one of two unique values, either trueor false. In some languages the values true and falsealso equate to numeric values. False is commonly 0 and trueany non-zero value. In JavaScript this is not the case. The value false does not test equal against zero. However, a false Boolean value does become zero when converted to a number. If you create a Boolean object and set it to the value true, you cannot convert it to a number with the toNumber()method, because this generates a run-time error. However, you can coerce the Boolean value into a numeric value by preceding it with a unary plus sign. So +true is a numeric primitive and yields the value 1, while falseis converted to zero. See also: false, JavaScript to Java values, true Cross-references: ECMA 262 edition 2 section 4.3.13 ECMA 262 edition 3 section 4.3.13 Wrox Instant JavaScript page 14 boolean (Reserved word) Reserved for future language enhancements. The boolean keyword represents both a Java data type and the native Boolean primitive data type in JavaScript. This suggests some potential extensions of JavaScript interfaces to access Java applet parameters and return values. See also: java.lang.Boolean, LiveConnect, Reserved word Cross-references: ECMA 262 edition 2 section 7.4.3 ECMA 262 edition 3 section 7.5.3

JavaScript Programmer’s Reference Warnings: . Note that the default values are platform-dependant and although it is only a couple of pixels difference it can throw off the layout of a page significantly if you make the wrong assumption. See also: BODY.bottomMargin BODY.vLink (Property) The color of visited links within the page. Availability: DOM level 1 JavaScript 1.5 JScript 3.0 Internet Explorer 4.0 Netscape 6.0 Property/method value type: String primitive JavaScript syntax: -myBODY.vLink This value controls the text of visited links in the document body. You should use the normal color values to define the required color. This corresponds to the VLINKattribute in the tag. Now that the style control facilities are more sophisticated, this tag attribute is likely to fall into disuse. Note also that its property name is not consistent with its counterpart, the document.vlinkColor property whose value it reflects. See also: BODY.aLink, BODY.link, BODY.text, Document.alinkColor, Document.bgColor, Document.fgColor, Document.linkColor, Document.vlinkColor, HTML object Bookmarklets (Advice) A means of storing fragments of JavaScript for execution as bookmarks. Creating a javascript: URL with some attached JavaScript code and storing it in the bookmarks or favorites of your browser is a way of setting up some really useful debugging tools. It seems to work in most browsers, although some have a size limit on the URL that you can use. See also: JavaScript Bookmark URLs, JavaScript interactive URL, javascript:URL

B BODY.text (Property) BODY.text (Property) The color of body text within the page. Availability: DOM level 1 JavaScript 1.5 JScript 3.0 Internet Explorer 4.0 Netscape 6.0 Property/method value type: String primitive JavaScript syntax: -myBODY.text This value controls the foreground text in the document body. You should use the normal color values to define the required color. This is the default text color for the document. It corresponds to the TEXT attribute in the tag. Default foreground text is colored according to this setting unless it is in an tag when the alinkColor, linkColor and vlinkColor properties override it. The foreground text color can be changed inline with the HTML tag attribute. Now that the style control facilities are more sophisticated, this tag attribute is likely to fall into disuse. Note also that its property name is not consistent with its counterpart, the document.fgColor property whose value it reflects. BODY.aLink, BODY.link, BODY.vLink, Color names, Color value, Document.alinkColor, Document.bgColor, Document.fgColor, Document.linkColor, Document.vlinkColor, HTML object See also: BODY.topMargin (Property) A margin value at the top of the document window. Availability: JScript 3.0 Internet Explorer 4.0 Property/method value type: Number primitive JavaScript syntax: IE myBODY.topMargin Normally, you would not need to specify this property. It allows the document to have some clear space at the top so for example the content could be made to scroll completely off the screen when it is loaded. The distance is measured in pixels and can range from zero (which is the default) to any reasonably sensible value. Making it any bigger than the screen size is pointless. This corresponds to the style.marginTop property and the margin-top attribute that is defined in a style sheet.