Chapter

11

Navigator JavaScript Reference

abs

Method. Returns the absolute value of a number.

Syntax

Math.abs(number)

Parameters

number is any numeric expression or a property of an existing object.

Method of

Math

Examples

The following function returns the absolute value of the variable x:

function getAbs(x) {
   return Math.abs(x)
}

acos

Method. Returns the arc cosine (in radians) of a number.

Syntax

Math.acos(number)

Parameters

number is a numeric expression between -1 and 1, or a property of an existing object.

Method of

Math

Description

The acos method returns a numeric value between zero and pi radians. If the value of number is outside this range, it returns zero.

Examples

The following function returns the arc cosine of the variable x:

function getAcos(x) {
   return Math.acos(x)
}
If you pass getAcos the value -1, it returns 3.141592653589793; if you pass it the value two, it returns zero because two is out of range.

See also

asin, atan, cos, sin, tan methods

action

Property. A string specifying a destination URL for form data that is submitted.

Syntax

formName.action

Parameters

formName is either the name of a form or an element in the forms array.

Property of

form

Description

The action property is a reflection of the ACTION attribute of the FORM tag. Each section of a URL contains different information. See the location object for a description of the URL components.

You can set the action property at any time.

Examples

The following example sets the action property of the musicForm form to the value of the variable urlName:

document.musicForm.action=urlName

See also

encoding, method, target properties; form object

alert

Method. Displays an Alert dialog box with a message and an OK button.

Syntax

alert("message")

Parameters

message is any string or a property of an existing object.

Method of

window object

Description

Use the alert method to display a message that does not require a user decision. The message argument specifies a message that the dialog box contains.

Although alert is a method of the window object, you do not need to specify a windowReference when you call it. For example, windowReference.alert() is unnecessary.

Examples

In the following example, the testValue function checks the name entered by a user in the text object of a form to make sure that it is no more than eight characters in length. This example uses the alert method to prompt the user to enter a valid value.

function testValue(textElement) {
   if (textElement.length > 8) {
      alert("Please enter a name that is 8 characters or less")
   }
}
You can call the testValue function in the onBlur event handler of a form's text object, as shown in the following example:

Name: <INPUT TYPE="text" NAME="userName"
   onBlur="testValue(userName.value)">

See also

confirm, prompt methods

alinkColor

Property. A string specifying the color of an active link (after mouse-button down, but before mouse-button up).

Syntax

document.alinkColor

Property of

document

Description

The alinkColor property is expressed as a hexadecimal RGB triplet or as one of the string literals listed in "Color values". This property is the JavaScript reflection of the ALINK attribute of the BODY tag. You cannot set this property after the HTML source has been through layout.

If you express the color as a hexadecimal RGB triplet, you must use the format rrggbb. For example, the hexadecimal RGB values for salmon are red=FA, green=80, and blue=72, so the RGB triplet for salmon is "FA8072."

Examples

The following example sets the color of active links using a string literal:

document.alinkColor="aqua"
The following example sets the color of active links to aqua using a hexadecimal triplet:

document.alinkColor="00FFFF"

See also

bgColor, fgColor, linkColor, vlinkColor properties

anchor method

Method. Creates an HTML anchor that is used as a hypertext target.

Syntax

text.anchor(nameAttribute)

Parameters

text is any string or a property of an existing object.

nameAttribute is any string or a property of an existing object.

Method of

string

Description

Use the anchor method with the write or writeln methods to programmatically create and display an anchor in a document. Create the anchor with the anchor method, and then call write or writeln to display the anchor in a document. In LiveWire, use the write function to display the anchor.

In the syntax, the text string represents the literal text that you want the user to see. The nameAttribute string represents the NAME attribute of the A tag.

Anchors created with the anchor method become elements in the anchors array. See the anchor object for information about the anchors array.

Examples

The following example opens the msgWindow window and creates an anchor for the Table of Contents:

var myString="Table of Contents"

msgWindow.document.writeln(myString.anchor("contents_anchor"))
The previous example produces the same output as the following HTML:

<A NAME="contents_anchor">Table of Contents</A>
In LiveWire, you can generate this HTML by calling the write function instead of using document.writeln.

See also

link method

anchor object

Object. A place in a document that is the target of a hypertext link.

HTML syntax

To define an anchor, use standard HTML syntax:

<A [HREF=locationOrURL]
   NAME="anchorName"
   [TARGET="windowName"]>
   anchorText
</A>
You can also define an anchor using the anchor method.

HTML attributes

HREF=locationOrURL is used only if the anchor is also a link. It identifies a destination anchor or URL for the link. See the link object for details.

NAME="anchorName" specifies a name for the anchor. A link to the anchor uses this value for its HREF attribute.

TARGET="windowName" is used only if the anchor is also a link. It specifies the window that the link is loaded into. See the link object for details.

anchorText specifies the text or HTML source to display at the anchor.

Property of

document

Description

If an anchor object is also a link object, the object has entries in both the anchors and links arrays.

The anchors array

You can reference the anchor objects in your code by using the anchors array. This array contains an entry for each A tag containing a NAME attribute in a document in source order. For example, if a document contains three named anchors, these anchors are reflected as document.anchors[0], document.anchors[1], and document.anchors[2].

To use the anchors array:

1. document.anchors[index]
2. document.anchors.length
index is an integer representing an anchor in a document.

To obtain the number of anchors in a document, use the length property: document.anchors.length. If a document names anchors in a systematic way using natural numbers, you can use the anchors array and its length property to validate an anchor name before using it in operations such as setting location.hash. See the example below.

Elements in the anchors array are read-only. For example, the statement document.anchors[0]="anchor1" has no effect.

Properties

The anchors object has no properties.

The anchors array has one property, length, that reflects the number of named anchors in the document.

Methods

None

Event handlers

None

Examples

Example 1: an anchor. The following example defines an anchor for the text "Welcome to JavaScript":

<A NAME="javascript_intro"><H2>Welcome to JavaScript</H2></A>
If the preceding anchor is in a file called intro.html, a link in another file could define a jump to the anchor as follows:

<A HREF="intro.html#javascript_intro">Introduction</A>
Example 2: anchors array. The following example opens two windows. The first window contains a series of buttons that set location.hash in the second window to a specific anchor. The second window defines four anchors named "0," "1," "2," and "3." (The anchor names in the document are therefore 0, 1, 2, ... (document.anchors.length-1).) When a button is pressed in the first window, the onClick event handler verifies that the anchor exists before setting window2.location.hash to the specified anchor name.

link1.html, which defines the first window and its buttons, contains the following code:

<HTML>
<HEAD>
<TITLE>Links and Anchors: Window 1</TITLE>
</HEAD>
<BODY>
<SCRIPT>
window2=open("link2.html","secondLinkWindow",
	"scrollbars=yes,width=250, height=400")
function linkToWindow(num) {
   if (window2.document.anchors.length > num)
      window2.location.hash=num
   else
      alert("Anchor does not exist!")
}
</SCRIPT>
<B>Links and Anchors</B>
<FORM>
<P>Click a button to display that anchor in window #2
<P><INPUT TYPE="button" VALUE="0" NAME="link0_button"
   onClick="linkToWindow(this.value)">
<INPUT TYPE="button" VALUE="1" NAME="link0_button"
   onClick="linkToWindow(this.value)">
<INPUT TYPE="button" VALUE="2" NAME="link0_button"
   onClick="linkToWindow(this.value)">
<INPUT TYPE="button" VALUE="3" NAME="link0_button"
   onClick="linkToWindow(this.value)">
<INPUT TYPE="button" VALUE="4" NAME="link0_button"
   onClick="linkToWindow(this.value)">
</FORM>
</BODY>
</HTML>
link2.html, which contains the anchors, contains the following code:

<HTML>
<HEAD>
<TITLE>Links and Anchors: Window 2</TITLE>
</HEAD>
<BODY>
<A NAME="0"><B>Some numbers</B> (Anchor 0)</A>
<UL><LI>one
<LI>two
<LI>three
<LI>four</UL>

<P><A NAME="1"><B>Some colors</B> (Anchor 1)</A>
<UL><LI>red
<LI>orange
<LI>yellow
<LI>green</UL>

<P><A NAME="2"><B>Some music types</B> (Anchor 2)</A>
<UL><LI>R&B
<LI>Jazz
<LI>Soul
<LI>Reggae
<LI>Rock</UL>

<P><A NAME="3"><B>Some countries</B> (Anchor 3)</A>
<UL><LI>Afghanistan
<LI>Brazil
<LI>Canada
<LI>Finland
<LI>India</UL>
</BODY>
</HTML>

See also

link object, anchor method

anchors

Property. An array of objects corresponding to named anchors in source order. See the anchor object for information.

appCodeName

Property. A string specifying the code name of the browser.

Syntax

navigator.appCodeName

Property of

navigator

Description

appCodeName is a read-only property.

Examples

The following example displays the value of the appCodeName property:

document.write("The value of navigator.appCodeName is " +
   navigator.appCodeName)
For Navigator 2.0, this displays the following:

The value of navigator.appCodeName is Mozilla

See also

appName, appVersion, userAgent properties

appName

Property. A string specifying the name of the browser.

Syntax

navigator.appName

Property of

navigator

Description

appName is a read-only property.

Examples

The following example displays the value of the appName property:

document.write("The value of navigator.appName is " +
   navigator.appName)
For Navigator 2.0, this displays the following:

The value of navigator.appName is Netscape

See also

appCodeName, appVersion, userAgent properties

appVersion

Property. A string specifying version information for the Navigator.

Syntax

navigator.appVersion

Property of

navigator

Description

The appVersion property specifies version information in the following format:

releaseNumber (platform; country)

The values contained in this format are the following:

Examples

Example 1. The following example displays version information for the Navigator:

document.write("The value of navigator.appVersion is " +
   navigator.appVersion)
For Navigator 2.0 on Windows 95, this displays the following:

The value of navigator.appVersion is 2.0 (Win95, I)
Example 2. The following example populates a textarea object with newline characters separating each line. Because the newline character varies from platform to platform, the example tests the appVersion property to determine whether the user is running Windows (appVersion contains "Win" for all versions of Windows). If the user is running Windows, the newline character is set to rn; otherwise, it's set to n, which is the newline character for Unix and Macintosh.

<SCRIPT>
var newline=null
function populate(textareaObject){
   if (navigator.appVersion.lastIndexOf('Win') != -1)
      newline="rn"
      else newline="n"
   textareaObject.value="line 1" + newline + "line 2" + newline 
	+ "line 3"
}
</SCRIPT>
<FORM NAME="form1">
<BR><TEXTAREA NAME="testLines" ROWS=8 COLS=55></TEXTAREA>
<P><INPUT TYPE="button" VALUE="Populate the textarea object"
   onClick="populate(document.form1.testLines)">
</TEXTAREA>
</FORM>

See also

appCodeName, appName, userAgent properties

arguments array

Property. An array corresponding to elements of a function.

Syntax

1. functionName.arguments[index]
2. functionName.arguments.length

Parameters

functionName is the name of a function you have created.

index is an integer representing an element of a function.

Property of

The arguments array is a property of any user-defined function.

Description

You can call a function with more arguments than it is formally declared to accept by using the arguments array. This technique is useful if a function can be passed a variable number of arguments. You can use arguments.length to determine the number of arguments passed to the function, and then treat each argument by using the arguments array.

The arguments array is available only within a function declaration. Attempting to access the arguments array outside a function declaration results in an error.

Properties

The arguments array has one property, length, that reflects the number of arguments to the function.

Examples

This example defines a function that creates HTML lists. The only formal argument for the function is a string that is "U" if the list is to be unordered (bulleted), or "O" if the list is to be ordered (numbered). The function is defined as follows:

function list(type) {
   document.write("<" + type + "L>")
   for (var i=1; i<list.arguments.length; i++) {
   document.write("<LI>" + list.arguments[i])
   document.write("</" + type + "L>") }
}
You can pass any number of arguments to this function, and it displays each argument as an item in the type of list indicated. For example, the following call to the function

list("U", "One", "Two", "Three")
results in this output:

<UL>
<LI>One
<LI>Two
<LI>Three
</UL>
In LiveWire, you can display the same output by calling the write function instead of using document.write.

arguments property

Property. An array of elements in a function. See the arguments array for information.

asin

Method. Returns the arc sine (in radians) of a number.

Syntax

Math.asin(number)

Parameters

number is a numeric expression between -1 and 1, or a property of an existing object.

Method of

Math

Description

The asin method returns a numeric value between -pi/2 and pi/2 radians. If the value of number is outside this range, it returns zero.

Examples

The following function returns the arc sine of the variable x:

function getAsin(x) {
   return Math.asin(x)
}
If you pass getAsin the value one, it returns 1.570796326794897 (pi/2); if you pass it the value two, it returns zero because two is out of range.

See also

acos, atan, cos, sin, tan methods

atan

Method. Returns the arc tangent (in radians) of a number.

Syntax

Math.atan(number)

Parameters

number is either a numeric expression or a property of an existing object, representing the tangent of an angle.

Method of

Math

Description

The atan method returns a numeric value between -pi/2 and pi/2 radians.

Examples

The following function returns the arc tangent of the variable x:

function getAtan(x) {
   return Math.atan(x)
}
If you pass getAtan the value 1, it returns 0.7853981633974483; if you pass it the value .5, it returns 0.4636476090008061.

See also

acos, asin, cos, sin, tan methods

back

Method. Loads the previous URL in the history list.

Syntax

history.back()

Method of

history

Description

This method performs the same action as a user choosing the Back button in the Navigator. The back method is the same as history.go(-1).

Examples

The following custom buttons perform the same operations as the Navigator Back and Forward buttons:

<P><INPUT TYPE="button" VALUE="< Back"
   onClick="history.back()">
<P><INPUT TYPE="button" VALUE="> Forward"
   onClick="history.forward()">

See also

forward, go methods

bgColor

Property. A string specifying the color of the document background.

Syntax

document.bgColor

Property of

document

Description

The bgColor property is expressed as a hexadecimal RGB triplet or as one of the string literals listed in "Color values". This property is the JavaScript reflection of the BGCOLOR attribute of the BODY tag. The default value of this property is set by the user on the Colors tab of the Preferences dialog box, which is displayed by choosing General Preferences from the Options menu.

You can set the bgColor property at any time.

If you express the color as a hexadecimal RGB triplet, you must use the format rrggbb. For example, the hexadecimal RGB values for salmon are red=FA, green=80, and blue=72, so the RGB triplet for salmon is "FA8072."

Examples

The following example sets the color of the document background to aqua using a string literal:

document.bgColor="aqua"
The following example sets the color of the document background to aqua using a hexadecimal triplet:

document.bgColor="00FFFF"

See also

alinkColor, fgColor, linkColor, vlinkColor properties

big

Method. Causes a string to be displayed in a big font as if it were in a BIG tag.

Syntax

stringName.big()

Parameters

stringName is any string or a property of an existing object.

Method of

string

Description

Use the big method with the write or writeln methods to format and display a string in a document. In LiveWire, use the write function to display the string.

Examples

The following example uses string methods to change the size of a string:

var worldString="Hello, world"

document.write(worldString.small())
document.write("<P>" + worldString.big())
document.write("<P>" + worldString.fontsize(7))
The previous example produces the same output as the following HTML:

<SMALL>Hello, world</SMALL>
<P><BIG>Hello, world</BIG>
<P><FONTSIZE=7>Hello, world</FONTSIZE>
In LiveWire, you can generate this HTML by calling the write function instead of using document.write.

See also

fontsize, small methods

blink

Method. Causes a string to blink as if it were in a BLINK tag.

Syntax

stringName.blink()

Parameters

stringName is any string or a property of an existing object.

Method of

string

Description

Use the blink method with the write or writeln methods to format and display a string in a document. In LiveWire, use the write function to display the string.

Examples

The following example uses string methods to change the formatting of a string:

var worldString="Hello, world"

document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())
The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>
In LiveWire, you can generate this HTML by calling the write function instead of using document.write.

See also

bold, italics, strike methods

blur

Method. Removes focus from the specified object.

Syntax

1. passwordName.blur()
2. selectName.blur()
3. textName.blur()
4. textareaName.blur()

Parameters

passwordName is either the value of the NAME attribute of a password object or an element in the elements array.

selectName is either the value of the NAME attribute of a select object or an element in the elements array.

textName is either the value of the NAME attribute of a text object or an element in the elements array.

textareaName is either the value of the NAME attribute of a textarea object or an element in the elements array.

Method of

password object, select object, text object, textarea object

Description

Use the blur method to remove focus from a specific form element.

Examples

The following example removes focus from the password element userPass:

userPass.blur()
This example assumes that the password is defined as

<INPUT TYPE="password" NAME="userPass">

See also

focus method, select method

bold

Method. Causes a string to be displayed as bold as if it were in a B tag.

Syntax

stringName.bold()

Parameters

stringName is any string or a property of an existing object.

Method of

string

Description

Use the bold method with the write or writeln methods to format and display a string in a document. In LiveWire, use the write function to display the string.

Examples

The following example uses string methods to change the formatting of a string:

var worldString="Hello, world" 
document.write(worldString.blink())
document.write("<P>" + worldString.bold())
document.write("<P>" + worldString.italics())
document.write("<P>" + worldString.strike())
The previous example produces the same output as the following HTML:

<BLINK>Hello, world</BLINK>
<P><B>Hello, world</B>
<P><I>Hello, world</I>
<P><STRIKE>Hello, world</STRIKE>
In LiveWire, you can generate this HTML by calling the write function instead of using document.write.

See also

blink, italics, strike methods

button

Object. A pushbutton on an HTML form.

HTML syntax

To define a button:

<INPUT
   TYPE="button"
   NAME="buttonName"
   VALUE="buttonText"
   [onClick="handlerText"]>

HTML attributes

NAME="buttonName" specifies the name of the button object. You can access this value using the name property.

VALUE="buttonText" specifies the label to display on the button face. You can access this value using the value property.

Syntax

To use a button object's properties and methods:

1. buttonName.propertyName
2. buttonName.methodName(parameters)
3. formName.elements[index].propertyName
4. formName.elements[index].methodName(parameters)

Parameters

buttonName is the value of the NAME attribute of a button object.

formName is either the value of the NAME attribute of a form object or an element in the forms array.

index is an integer representing a button object on a form.

propertyName is one of the properties listed below.

methodName is one of the methods listed below.

Property of

form

Description

A button object on a form looks as follows:

A button object is a form element and must be defined within a FORM tag.

The button object is a custom button that you can use to perform an action you define. The button executes the script specified by its onClick event handler.

Properties

The button object has the following properties:
Property

Description

name Reflects the NAME attribute
value Reflects the VALUE attribute

Methods

click

Event handlers

onClick

Examples

The following example creates a button named calcButton. The text "Calculate" is displayed on the face of the button. When the button is clicked, the function calcFunction is called.

<INPUT TYPE="button" VALUE="Calculate" NAME="calcButton"
   onClick="calcFunction(this.form)">

See also

form object, reset object, submit object

ceil

Method. Returns the least integer greater than or equal to a number.

Syntax

Math.ceil(number)

Parameters

number is any numeric expression or a property of an existing object.

Method of

Math

Examples

The following function returns the ceil value of the variable x:

function getCeil(x) {
   return Math.ceil(x)
}
If you pass getCeil the value 45.95, it returns 46; if you pass it the value -45.95, it returns -45.

See also

floor method

charAt

Method. Returns the character at the specified index.

Syntax

stringName.charAt(index)

Parameters

stringName is any string or a property of an existing object.

index is any integer from zero to stringName.length - 1, or a property of an existing object.

Method of

string

Description

Characters in a string are indexed from left to right. The index of the first character is zero, and the index of the last character is stringName.length - 1. If the index you supply is out of range, JavaScript returns an empty string.

Examples

The following example displays characters at different locations in the string "Brave new world":

var anyString="Brave new world"

document.write("The character at index 0 is " + anyString.charAt(0))
document.write("The character at index 1 is " + anyString.charAt(1))
document.write("The character at index 2 is " + anyString.charAt(2))
document.write("The character at index 3 is " + anyString.charAt(3))
document.write("The character at index 4 is " + anyString.charAt(4))
In LiveWire, you can display the same output by calling the write function instead of using document.write.

See also

indexOf, lastIndexOf methods

checkbox

Object. A checkbox on an HTML form. A checkbox is a toggle switch that lets the user set a value on or off.

HTML syntax

To define a checkbox, use standard HTML syntax with the addition of the onClick event handler:

<INPUT
   TYPE="checkbox"
   NAME="checkboxName"
   VALUE="checkboxValue"
   [CHECKED]
   [onClick="handlerText"]>
   textToDisplay

HTML attributes

NAME="checkboxName" specifies the name of the checkbox object. You can access this value using the name property.

VALUE="checkboxValue" specifies a value that is returned to the server when the checkbox is selected and the form is submitted. This defaults to "on." You can access this value using the value property.

CHECKED specifies that the checkbox is displayed as checked. You can access this value using the defaultChecked property.

textToDisplay specifies the label to display beside the checkbox.

Syntax

To use a checkbox object's properties and methods:

1. checkboxName.propertyName
2. checkboxName.methodName(parameters)
3. formName.elements[index].propertyName
4. formName.elements[index].methodName(parameters)

Parameters

checkboxName is the value of the NAME attribute of a checkbox object.

formName is either the value of the NAME attribute of a form object or an element in the forms array.

index is an integer representing a checkbox object on a form.

propertyName is one of the properties listed below.

methodName is one of the methods listed below.

Property of

form

Description

A checkbox object on a form looks as follows:

Overnight delivery

A checkbox object is a form element and must be defined within a FORM tag.

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

The checkbox object has the following properties:
Property

Description

checked Boolean property that reflects the current state of the checkbox: true for checked or false for unchecked. Lets you programmatically check a checkbox
defaultChecked Boolean property that reflects the CHECKED attribute: true if checkbox is checked by default, false otherwise.
name Reflects the NAME attribute
value Reflects the VALUE attribute

Methods

click

Event handlers

onClick

Examples

Example 1. The following example displays a group of four checkboxes that all appear checked by default:

<B>Specify your music preferences (check all that apply):</B>
<BR><INPUT TYPE="checkbox" NAME="musicpref_rnb" CHECKED> R&B
<BR><INPUT TYPE="checkbox" NAME="musicpref_jazz" CHECKED> Jazz
<BR><INPUT TYPE="checkbox" NAME="musicpref_blues" CHECKED> Blues
<BR><INPUT TYPE="checkbox" NAME="musicpref_newage" CHECKED> New Age
Example 2. The following example contains a form with three text boxes and one checkbox. The user can use the checkbox to choose whether the text fields are converted to uppercase. Each text field has an onChange event handler that converts the field value to uppercase if the checkbox is checked. The checkbox has an onClick event handler that converts all fields to uppercase when the user checks the checkbox.

<HTML>
<HEAD>
<TITLE>Checkbox object example</TITLE>
</HEAD>
<SCRIPT>
function convertField(field) {
   if (document.form1.convertUpper.checked) {
      field.value = field.value.toUpperCase()}
}
function convertAllFields() {
   document.form1.lastName.value = document.form1.lastName.value.toUpperCase()
   document.form1.firstName.value = document.form1.firstName.value.toUpperCase()
   document.form1.cityName.value = document.form1.cityName.value.toUpperCase()
}
</SCRIPT>
<BODY>
<FORM NAME="form1">
<B>Last name:</B>
<INPUT TYPE="text" NAME="lastName" SIZE=20 onChange="convertField(this)">
<BR><B>First name:</B>
<INPUT TYPE="text" NAME="firstName" SIZE=20 onChange="convertField(this)">
<BR><B>City:</B>
<INPUT TYPE="text" NAME="cityName" SIZE=20 onChange="convertField(this)">
<P><INPUT TYPE="checkBox" NAME="convertUpper"
   onClick="if (this.checked) {convertAllFields()}"
   > Convert fields to upper case
</FORM>
</BODY>
</HTML>

See also

form, radio objects

checked

Property. A Boolean value specifying the selection state of a checkbox object or radio button.

Syntax

1. checkboxName.checked
2. radioName[index].checked

Parameters

checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.

radioName is the value of the NAME attribute of a radio object.

index is an integer representing a radio button in a radio object.

Property of

checkbox, radio

Description

If a checkbox or radio button is selected, the value of its checked property is true; otherwise, it is false.

You can set the checked property at any time. The display of the checkbox or radio button updates immediately when you set the checked property.

Examples

The following example examines an array of radio buttons called musicType on the musicForm form to determine which button is selected. The VALUE attribute of the selected button is assigned to the checkedButton variable.

function stateChecker() {
   var checkedButton = ""
   for (var i in document.musicForm.musicType) {
      if (document.musicForm.musicType[i].checked=="1") {
         checkedButton=document.musicForm.musicType[i].value
      }
   }
}

See also

defaultChecked property

clear

Method. Clears the document in a window.

Syntax

document.clear()

Method of

document

Description

The clear method empties the content of a window, regardless of how the content of the window has been painted.

Examples

When the following function is called, the clear method empties the contents of the msgWindow window:

function windowCleaner() {
   msgWindow.document.clear()
   msgWindow.document.close()
}

See also

close (document object), open (document object), write, writeln methods

clearTimeout

Method. Cancels a timeout that was set with the setTimeout method.

Syntax

clearTimeout(timeoutID)

Parameters

timeoutID is a timeout setting that was returned by a previous call to the setTimeout method.

Method of

frame object, window object

Description

See the description for the setTimeout method.

Examples

See the examples for the setTimeout method.

See also

setTimeout method

click

Method. Simulates a mouse-click on the calling form element.

Syntax

1. buttonName.click()
2. radioName[index].click()
3. checkboxName.click()

Parameters

buttonName is either the value of the NAME attribute of a button, reset, or submit object or an element in the elements array.

radioName is the value of the NAME attribute of a radio object or an element in the elements array.

index is an integer representing a radio button in a radio object.

checkboxName is either the value of the NAME attribute of a checkbox object or an element in the elements array.

Method of

button, checkbox, radio, reset, submit object

Description

The effect of the click method varies according to the calling element:

  • For button, reset, and submit, performs the same action as clicking the button.
  • For a radio, selects a radio button.
  • For a checkbox, checks the checkbox and sets its value to "on."

    Examples

    The following example toggles the selection status of the first radio button in the musicType radio object on the musicForm form:

    document.musicForm.musicType[0].click()
    
    The following example toggles the selection status of the newAge checkbox on the musicForm form:

    document.musicForm.newAge.click()
    

    close (document object)

    Method. Closes an output stream and forces data sent to layout to display.

    Syntax

    document.close()
    

    Method of

    document

    Description

    The close method closes a stream opened with the document.open() method. If the stream was opened to layout, the close method forces the content of the stream to display. Font style tags, such as BIG and CENTER, automatically flush a layout stream.

    The close method also stops the "meteor shower" in the Netscape icon and displays "Document: Done" in the status bar.

    Examples

    The following function calls document.close() to close a stream that was opened with document.open(). The document.close() method forces the content of the stream to display in the window.

    function windowWriter1() {
       var myString = "Hello, world!"
       msgWindow.document.open()
       msgWindow.document.write(myString + "<P>")
       msgWindow.document.close()
    }
    

    See also

    clear, open (document object), write, writeln methods

    close (window object)

    Method. Closes the specified window.

    Syntax

    windowReference.close()
    

    Parameters

    windowReference is a valid way of referring to a window, as described in the window object.

    Method of

    window object

    Description

    The close method closes the specified window. If you call close without specifying a windowReference, JavaScript closes the current window.

    In event handlers, you must specify window.close() instead of simply using close(). Due to the scoping of static objects in JavaScript, a call to close() without specifying an object name is equivalent to document.close().

    Examples

    Any of the following examples closes the current window:

    window.close()
    self.close()
    close()
    
    The following example closes the messageWin window:

    messageWin.close()
    
    This example assumes that the window was opened in a manner similar to the following:

    messageWin=window.open("")
    

    See also

    open (window object) method

    confirm

    Method. Displays a Confirm dialog box with the specified message and OK and Cancel buttons.

    Syntax

    confirm("message")
    

    Parameters

    message is any string or a property of an existing object.

    Method of

    window object

    Description

    Use the confirm method to ask the user to make a decision that requires either an OK or a Cancel. The message argument specifies a message that prompts the user for the decision. The confirm method returns true if the user chooses OK and false if the user chooses Cancel.

    Although confirm is a method of the window object, you do not need to specify a windowReference when you call it. For example, windowReference.confirm() is unnecessary.

    Examples

    This example uses the confirm method in the confirmCleanUp function to confirm that the user of an application really wants to quit. If the user chooses OK, the custom cleanUp function closes the application.

    function confirmCleanUp() {
       if (confirm("Are you sure you want to quit this application?")) {
          cleanUp()
       }
    }
    
    You can call the confirmCleanUp function in the onClick event handler of a form's pushbutton, as shown in the following example:

    <INPUT TYPE="button" VALUE="Quit" onClick="confirmCleanUp()">
    

    See also

    alert, prompt methods

    cookie

    Property. String value of a cookie, which is a small piece of information stored by the Navigator in the cookies.txt file.

    Syntax

    document.cookie
    

    Property of

    document

    Description

    Use string methods such as substring, charAt, indexOf, and lastIndexOf to determine the value stored in the cookie. See the Appendix C, "Netscape cookies" for a complete specification of the cookie syntax.

    You can set the cookie property at any time.

    The "expires=" component in the cookie file sets an expiration date for the cookie, so it persists beyond the current browser session. This date string is formatted as follows:

    Wdy, DD-Mon-YY HH:MM:SS GMT
    
    This format represents the following values:

  • Wdy is a string representing the full name of the day of the week.
  • DD is an integer representing the day of the month.
  • Mon is a string representing the three-character abbreviation of the month.
  • YY is an integer representing the last two digits of the year.
  • HH, MM, and SS are two-digit representations of hours, minutes, and seconds, respectively. For example, a valid cookie expiration date is

    expires=Wednesday, 09-Nov-99 23:12:40 GMT
    
    The cookie date format is the same as the date returned by toGMTString, with the following exceptions:

  • Dashes are added between the day, month, and year.
  • The year is a two-digit value for cookies.

    Examples

    The following function uses the cookie property to record a reminder for users of an application. The cookie expiration date is set to one day after the date of the reminder.

    function RecordReminder(time, expression) {
       // Record a cookie of the form "@<T>=<E>" to map
       // from <T> in milliseconds since the epoch,
       // returned by Date.getTime(), onto an encoded expression,
       // <E> (encoded to contain no white space, semicolon,
       // or comma characters)
       document.cookie = "@" + time + "=" + expression + ";"
       // set the cookie expiration time to one day
       // beyond the reminder time
       document.cookie += "expires=" + cookieDate(time + 24*60*60*1000)
       // cookieDate is a function that formats the date
       //according to the cookie spec 
    }
    

    See also

    hidden object

    cos

    Method. Returns the cosine of a number.

    Syntax

    Math.cos(number)
    

    Parameters

    number is a numeric expression representing the size of an angle in radians, or a property of an existing object.

    Method of

    Math

    Description

    The cos method returns a numeric value between -1 and one, which represents the cosine of the angle.

    Examples

    The following function returns the cosine of the variable x:

    function getCos(x) {
       return Math.cos(x)
    }
    
    If x equals Math.PI/2, getCos returns 6.123031769111886e-017; if x equals Math.PI, getCos returns -1.

    See also

    acos, asin, atan, sin, tan methods


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