The following objects are available in JavaScript:
anchor applet button checkbox Date document form history link location Math password radioButton reset selection string submit text textArea window
NOTE: Each object topic indicates whether the object is part of the client (in Navigator), server (in LiveWire), or is common (built-in to JavaScript). Server objects are not included in this version of the documentation.
An anchor is a piece of text identified as the target of a hypertext link.
Syntax
To define an anchor, use standard HTML syntax :
<A NAME="anchorName"
anchorText
<A>
NAME specifies a tag that becomes an available hypertext target within the current document.
anchorText specifies the text to display at the anchor.
Description
You can reference the anchor objects in your code by using the anchors property of the document object. The anchors property is an array that contains an entry for each anchor in a document.
xxx to be supplied
Properties
xxx to be supplied
Methods
xxx to be supplied
Event handlers
None.
Examples
<A NAME="javascript_intro"><H2>Welcome to JavaScript</H2></A>
The applet object executes applets written in Java, not JavaScript. Java applets execute only on Netscape 2.0 and HotJava, and only on 32-bit platforms, such as Windows 95, Windows NT, and Unix. They do not execute on the 16-bit Windows platforms, such as Windows 3.1.
NAME specifies the name of the button object as a property of the enclosing form object and can be accessed using the name property. VALUE specifies the label to display on the button face and can be accessed using the value property.
Description
The button object is a custom button that you can use to perform an action you define.
Properties
name value
Methods
click
Event handlers
onClick
Examples
A custom button does not necessarily load a new page into the client; it merely executes the script specified by the onClick event handler. In the following example, myfunction() is a JavaScript function.
A checkbox object is a checkbox on an HTML form. A checkbox is a toggle switch that lets the user set a value on or off.
Syntax
To define a checkbox, use standard HTML syntax with the addition of the onClick event handler:
<INPUT
TYPE="checkbox"
NAME="objectName"
[CHECKED]
[onClick="handlerText"]> textToDisplay
Description
Use the checked property to specify whether the checkbox is currently checked. Use the defaultChecked property to specify whether the checkbox is checked when the form is loaded.
Properties
checked defaultChecked name value
Methods
click
Event handlers
onClick
Examples
<B>Specify your music preferences (check all that apply):</B>
JavaScript has a date object that enables you to work with dates and times. JavaScript handles dates very similar to the way Java handles dates: They have many of the same date methods, and both languages store dates internally as the number of milliseconds since January 1, 1970 00:00:00.
Syntax
To create a date object:
varName = new Date(parameters)
where varName is a JavaScript variable name for the date object being created; it can be a new object or a property of an existing object.
The parameters for the Date constructor can be any of the following:
ΓÇóNothing: creates today's date and time. For example, today = new Date() ΓÇóA string representing a date in the following form: "Month day, year hours:minutes:seconds". For example, Xmas95= new Date("December 25, 1995 13:30:00") If you omit hours, minutes, or seconds, the value will be set to zero. ΓÇóA set of integer values for year, month, and day. For example, Xmas95 = new Date(95,11,25) ΓÇóA set of values for year, month, day, hour, minute, and seconds For example, Xmas95 = new Date(95,11,25,9,30,0)
To use date methods:
dateObj.methodName(parameters)
Exceptions: The UTC and parse methods of date are static methods that you use as follows:
Date.UTC(params)
Date.parse(params)
Description
JavaScript does not have a date data type. However, the date object and its methods enable you to work with dates and times in your applications.
The date object has a large number of methods for setting, getting, and manipulating dates.
The document object contains information on the current document.
Syntax
To define a document object, use standard HTML syntax with the addition of the onLoad and onUnLoad event handlers:
<BODY
BACKGROUND="backgroundImage"
BGCOLOR="#backgroundColor"
FGCOLOR="#foregroundColor"
LINK="#unfollowedLinkColor"
ALINK="#activatedLinkColor"
VLINK="#followedLinkColor"
[onLoad="handlerText"]
[onUnLoad="handlerText"]><BODY>
BGCOLOR, FGCOLOR, LINK, ALINK, and VLINK are color names or color specifications in the format "#rrggbb".
Description
The <BODY>..<BODY>tag encloses an entire document, which is defined by the current URL. The entire body of the document (all other HTML elements for the document) goes within the <BODY>..<BODY>tag.
You can reference the anchors, forms, and links of a document by using the anchors, forms, and links properties. These properties are arrays that contain an entry for each anchor, form, or link in a document.
The document object's title property reflects the contents of <TITLE>..<TITLE> Other properties reflect the contents of the document; for example, bgColor reflects the background color, and lastModified reflects the time last modified. Some of the properties are reflections from HTML attributes; for example, the links property is a reflection of all the links in the document, and the forms property is a reflection of all the forms in the document.
Properties
alinkColor anchors bgColor fgColor forms lastModified linkColor links loadedDate location referrer title vlinkColor
A form lets users input text and make choices from form objects such as checkboxes, radio buttons, and selection lists. You can also use a form to post data to or retrieve data from a server.
Syntax
To define a form, use standard HTML syntax with the addition of the onSubmit event handler:
<FORM
NAME="objectName
TARGET="windowName"
ACTION="serverURL"
METHOD=GET | POST
[onSubmit="handlerText"]><FORM>
TARGET specifies the window that form responses go to. When you submit a form with a TARGET attribute, instead of seeing the server's responses in the same window that contained the form, you see them in a (possibly new) window.
ACTION specifies the URL of the server to which form field input information is sent.
METHOD specifies how information is sent to the server specified by ACTION. GET (the default) appends the input information to the URL which on most receiving systems becomes the value of the environment variable QUERY_STRING. POST sends the input information in a data body which is available on stdin with the data length set in the environment variable CONTENT_LENGTH.
Description
Each form in a document corresponds to a distinct object.
You can reference the form objects in your code by using the forms property of the document object. The forms property is an array that contains an entry for each form in a document.
You can reference a form's elements in your code by using the elements property. The elements property is an array that contains an entry for each element (such as a checkbox, radioButton, or text object) in a form.
The history object contains information on the URLs that the client has visited. This information is stored in a history list, and is accessible through the Navigator's Go menu.
Syntax
history.go(delta)
delta is an integer representing the offset of the destination URL in the history list.
Description
The history object is a linked list of URLs the user has visited, as shown in the Navigator's Go menu.
Properties
current length
Methods
back forward go
Event handlers
None.
Examples
The following example goes to the URL the user visited three clicks ago.
A link is a piece of text identified as a hypertext link. When the user clicks the link text, the link hypertext reference is loaded into its target window.
Syntax
To define a link, use standard HTML syntax with the addition of the onClick and onMouseOver event handlers:
<A HREF=locationOrURL
TARGET="windowName"
[onClick="handlerText"]
[onMouseOver="handlerText"]> linkText
<A>
HREF identifies a destination anchor or URL.
TARGET specifies the window that the link is loaded into.
linkText is rendered as a hypertext link to the URL.
Description
Each link object is a location object.
You can reference the link objects in your code by using the links property of the document object. The links property is an array that contains an entry for each link in a document.
Properties
target
Methods
xxx to be supplied
Event handlers
onClick onMouseOver
Examples
The following example creates a hypertext link to an anchor named javascript_intro.
<A HREF="#javascript_intro">Introduction to JavaScript</A>
The following example creates a hypertext link to a URL.
<A HREF="http://www.netscape.com">Netscape Home Page</A>
The built-in Math object has properties and methods for mathematical constants and functions. For example, the Math object's PI property has the value of pi.
Syntax
Math.propertyName
or
Math.methodName(parameters)
Description
You reference the constant PI as Math.PI. Constants are defined with the full precision of real numbers in JavaScript.
Similarly, you reference Math functions as methods. For example, the sine function is Math.sin(argument), where argument is the argument.
It is often convenient to use the with statement when a section of code uses several Math constants and methods, so you don't have to type "Math" repeatedly. For example,
with Math {
a = PI * r*r;
y = r*sin(theta)
x = r*cos(theta)
}
Properties
E LN10 LN2 PI SQRT1_2 SQRT2
Methods
abs acos asin atan ceil cos exp floor log max min pow random round sin sqrt tan
Event handlers
None. Built-in objects do not have event handlers.
A radioButton object is a set of radio buttons on an HTML form. A set of radio buttons lets the user choose one item from a list.
Syntax
To define a set of radio buttons, use standard HTML syntax with the addition of the onClick event handler:
<INPUT
TYPE="radio"
NAME="objectName"
VALUE="buttonValue"
[CHECKED]
[onClick="handlerText"]> textToDisplay
NAME should contain the same value for all radio buttons in a group.
Description
All radio buttons in a radio button group use the same name property. To access the individual radio buttons in your code, follow the object name with an index starting from zero, one for each button the same way you would for an array such as forms: document.forms[0].objectName[0] is the first, document.forms[0].objectName[1] is the second, etc.
Properties
checked defaultChecked index length name value
Methods
click
Event handlers
onClick
Examples
The following example defines a radio button group to choose among three catalogs. Each radio button is given the same name, NAME="choice", forming a group of buttons for which only one choice can be selected. The example also defines a text field that defaults to what was chosen via the radio buttons but that allows the user to type a nonstandard catalog name as well. JavaScript automatically sets the catalog name input field based on the radio buttons.
To define a reset button, use standard HTML syntax with the addition of the onClick event handler:
<INPUT
[NAME="objectName"]
TYPE="reset"
VALUE="buttonText"
[onClick="handlerText"]>
VALUE specifies the text to display on the button face and can be accessed using the value property.
Description
A reset button resets all elements in a form to their defaults.
Properties
name value
Methods
click
Event handlers
onClick
Examples
The following example displays a text object containing "CA". If the user types a different state abbreviation in the text object and then clicks the Clear Form button, the original value of "CA" is restored.
A selection object is a selection list or scrolling list on an HTML form. A selection list lets the user choose one item from a list. A scrolling list lets the user choose one or more items from a list.
Syntax
To define a selection object, use standard HTML syntax with the addition of the onBlur, onChange, and onFocus event handlers:
SIZE specifies the number of options visible when the form is displayed.
Description
You can reference the options of a selection object in your code by using the options property. The options property is an array that contains an entry for each option in a selection object. Each option has the properties listed below.
The options on selection objects can be updated dynamically. xxx NYI.
Properties
The selection object has the following properties: options selectedIndex
The options property has the following properties: defaultSelected index selected text value
Methods
click
Event handlers
onBlur onChange onFocus
Examples
The following example displays a selection list.
Choose the music type for your free CD:
<SELECT NAME="music_type_single">
<OPTION SELECTED> R&B <OPTION> Jazz <OPTION> Blues <OPTION> New Age</SELECT>
<P>Choose the music types for your free CDs:
<BR><SELECT NAME="music_type_multi" MULTIPLE>
<OPTION SELECTED> R&B <OPTION> Jazz <OPTION> Blues <OPTION> New Age</SELECT>
A submit object is a submit button on an HTML form.
Syntax
To define a submit button, use standard HTML syntax with the addition of the onClick event handler:
<INPUT
TYPE="submit"
NAME="objectName"
VALUE="buttonText"
[onClick="handlerText"]>
VALUE specifies the text to display on the button face and can be accessed using the value property.
Description
A submit button causes a form to be submitted.
Clicking a submit button submits a form to the program specified by the form's action property. This action always loads a new page into the client; it may be the same as the current page, if the action so specifies or is not specified.
A window object is the top-level object for each document, location, and history object group.
Syntax
xxx to be supplied
Description
The window object is the top-level object in the JavaScript client hierarchy. Because the existence of the current window is assumed, you don't have to reference the name of the window when you call its methods and assign its properties. For example, status="Jump to a new location" is a valid property assignment, and close() is a valid method call.
The self and window properties are synonyms for the current window, and you can optionally use them to refer to the current window. For example, you can close the current window by calling either window.close() or self.close(). You can use these properties to make your code more readable, or to disambiguate the property assignment self.status from a form called status.
See the methods and properties listed below for more examples.
You can reference a window's frame objects in your code by using the frames property. The frames property is an array that contains an entry for each frame in a window.
Properties
frames parent self top status defaultStatus
Methods
alert close confirm open prompt setTimeout clearTimeout
