Math.abs(number)
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:
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>
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 |
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:
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:
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:
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.
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:
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:
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