1. links[index].hash 2. location.hash
Description
The hash property specifies a portion of the URL. This property applies to http URLs only.
You can set the hash property at any time, although it is safer to set the href property to change a location. If the hash that you specify cannot be found in the current location, you will get an error.
See RFC 1738 (http://www.cis.ohio-state.edu/htbin/rfc/rfc1738.html) for complete information about the hash.
Examples
See the examples for the anchor object and the href property.
See also
host, hostname, href, pathname, port, protocol, search properties
hidden
Object. A text object that is suppressed from form display on an HTML form. A hidden object is used for passing name/value pairs when a form submits.
HTML syntax
To define a hidden object:
<INPUT
TYPE="hidden"
NAME="hiddenName"
[VALUE="textValue"]>
HTML attributes
NAME="hiddenName" specifies the name of the hidden object. You can access this value using the name property.
VALUE="textValue" specifies the initial value of the hidden object.
Syntax
To use a hidden object's properties:
1. hiddenName.propertyName
2. formName.elements[index].propertyName
Parameters
hiddenName is the value of the NAME attribute of a hidden 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 hidden object on a form.
propertyName is one of the properties listed below.
Property of
form
Description
A hidden object is a form element and must be defined within a FORM tag.
A hidden object cannot be seen or modified by a user, but you can programmatically change the value of the object by changing its value property. You can use hidden objects for client/server communication.
Properties
The hidden object has the following properties:
| Property | Description |
|---|---|
| name | Reflects the NAME attribute |
| value | Reflects the current value of the hidden object |
Methods
None
Event handlers
None
Examples
The following example uses a hidden object to store the value of the last object the user clicked. The form contains a "Display hidden value" button that the user can click to display the value of the hidden object in an Alert dialog box.
<HTML>
<HEAD>
<TITLE>Hidden object example</TITLE>
</HEAD>
<BODY>
<B>Click some of these objects, then click the "Display value" button
<BR>to see the value of the last object clicked.</B>
<FORM NAME="form1">
<INPUT TYPE="hidden" NAME="hiddenObject" VALUE="None">
<P>
<INPUT TYPE="button" VALUE="Click me" NAME="button1"
onClick="document.form1.hiddenObject.value=this.value">
<P>
<INPUT TYPE="radio" NAME="musicChoice" VALUE="soul-and-r&b"
onClick="document.form1.hiddenObject.value=this.value"> Soul and R&B
<INPUT TYPE="radio" NAME="musicChoice" VALUE="jazz"
onClick="document.form1.hiddenObject.value=this.value"> Jazz
<INPUT TYPE="radio" NAME="musicChoice" VALUE="classical"
onClick="document.form1.hiddenObject.value=this.value"> Classical
<P>
<SELECT NAME="music_type_single"
onFocus="document.form1.hiddenObject.value=this.options[this.selectedIndex].text">
<OPTION SELECTED> Red <OPTION> Orange <OPTION> Yellow
</SELECT>
<P><INPUT TYPE="button" VALUE="Display hidden value" NAME="button2"
onClick="alert('Last object clicked: ' + document.form1.hiddenObject.value)">
</FORM>
</BODY>
</HTML>
See also
cookie property
history
Object. Contains information on the URLs that the client has visited within a window. This information is stored in a history list and is accessible through the Navigator Go menu.
Syntax
To use a history object:
1. history.propertyName
2. history.methodName(parameters)
Parameters
propertyName is one of the properties listed below.
methodName is one of the methods listed below.
Property of
window object
Description
The history object is a linked list of URLs the user has visited, as shown in the Navigator Go menu.
Properties
The history object has one property, length, that reflects the number of entries in the history list.
Methods
history.go(-3)Example 2. You can use the history object with a specific window or frame. The following example causes window2 to go back one item in its window (or session) history:
window2.history.back()Example 3. The following example causes the second frame in a frameset to go back one item:
parent.frames[1].history.back()Example 4. The following example causes the frame named frame1 in a frameset to go back one item:
parent.frame1.history.back()Example 5. The following example causes the frame named frame2 in window2 to go back one item:
window2.frame2.history.back()
host
Property. A string specifying the server name, subdomain, and domain name.
Syntax
1. links[index].host
2. location.host
Parameters
index is an integer representing a link object.
Property of
link object, location object
Description
The host property specifies a portion of a URL. The host property is a substring of the hostname property. The hostname property is the concatenation of the host and port properties, separated by a colon. When the port property is null, the host property is the same as the hostname property.
You can set the host property at any time, although it is safer to set the href property to change a location. If the host that you specify cannot be found in the current location, you will get an error.
See Section 3.1 of RFC 1738 (http://www.cis.ohio-state.edu/htbin/rfc/rfc1738.html) for complete information about the hostname and port.
Examples
See the examples for the href property.
See also
hash, hostname, href, pathname, port, protocol, search properties
hostname
Property. A string containing the full hostname of the server, including the server name, subdomain, domain, and port number.
Syntax
1. links[index].hostname
2. location.hostname
Parameters
index is an integer representing a link object.
Property of
link object, location object
Description
The hostname property specifies a portion of a URL. The hostname property is the concatenation of the host and port properties, separated by a colon. When the port property is 80 (the default), the host property is the same as the hostname property.
You can set the hostname property at any time, although it is safer to set the href property to change a location. If the hostname that you specify cannot be found in the current location, you will get an error.
See Section 3.1 of RFC 1738 (http://www.cis.ohio-state.edu/htbin/rfc/rfc1738.html) for complete information about the hostname.
Examples
See the examples for the href property.
See also
hash, host, href, pathname, port, protocol, search properties
href
Property. A string specifying the entire URL.
Syntax
1. links[index].href
2. location.href
Parameters
index is an integer representing a link object.
Property of
link object, location object
Description
The href property specifies the entire URL. Other location object properties are substrings of the href property. You can set the href property at any time.
Omitting a property name from the location object is equivalent to specifying location.href. For example, the following two statements are equivalent and set the URL of the current window to the Netscape home page:
window.location.href="http://www.netscape.com/"
window.location="http://www.netscape.com/"
See RFC 1738 (http://www.cis.ohio-state.edu/htbin/rfc/rfc1738.html) for complete information about the URL.
Examples
In the following example, the window.open statement creates a window called newWindow and loads the specified URL into it. The document.write statements display all the properties of newWindow.location in a window called msgWindow.
newWindow=window.open
("http://home.netscape.com/comprod/products/navigator/
version_2.0/script/script_info/objects.html#checkbox_object")
msgWindow.document.write("newWindow.location.href = " +
newWindow.location.href + "<P>")
msgWindow.document.write("newWindow.location.protocol = " +
newWindow.location.protocol + "<P>")
msgWindow.document.write("newWindow.location.host = " +
newWindow.location.host + "<P>")
msgWindow.document.write("newWindow.location.hostName = " +
newWindow.location.hostName + "<P>")
msgWindow.document.write("newWindow.location.port = " +
newWindow.location.port + "<P>")
msgWindow.document.write("newWindow.location.pathname = " +
newWindow.location.pathname + "<P>")
msgWindow.document.write("newWindow.location.hash = " +
newWindow.location.hash + "<P>")
msgWindow.document.write("newWindow.location.search = " +
newWindow.location.search + "<P>")
msgWindow.document.close()
The previous example displays output such as the following:
newWindow.location.href =
http://home.netscape.com/comprod/products/navigator/
version_2.0/script/script_info/objects.html#checkbox_object
newWindow.location.protocol = http:
newWindow.location.host = home.netscape.com
newWindow.location.hostName = home.netscape.com
newWindow.location.port =
newWindow.location.pathname =
/comprod/products/navigator/version_2.0/script/
script_info/objects.html
newWindow.location.hash = #checkbox_object
newWindow.location.search =
See also
hash, host, hostname, pathname, port, protocol, search properties
index
Property. An integer representing the index of an option in a select object.
Syntax
selectName.options[indexValue].index
Parameters
selectName is either the value of the NAME attribute of a select object or an element in the elements array.
indexValue is an integer representing an option in a select object.
Property of
options array
Description
The number identifying the position of the option in the selection, starting from zero.
See also
defaultSelected, selected, selectedIndex properties
indexOf
Method. Returns the index within the calling string object of the first occurrence of the specified value, starting the search at fromIndex.
Syntax
stringName.indexOf(searchValue, [fromIndex])
Parameters
stringName is any string or a property of an existing object.
searchValue is a string or a property of an existing object, representing the value to search for.
fromIndex is the location within the calling string to start the search from. It can be 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 you do not specify a value for fromIndex, JavaScript assumes zero by default. If searchValue is not found, JavaScript returns -1.
Examples
The following example uses indexOf and lastIndexOf to locate values in the string "Brave new world."
var anyString="Brave new world"
//Displays 8
document.write("<P>The index of the first w from the beginning is " +
anyString.indexOf("w"))
//Displays 10
document.write("<P>The index of the first w from the end is " +
anyString.lastIndexOf("w"))
//Displays 6
document.write("<P>The index of 'new' from the beginning is " +
anyString.indexOf("new"))
//Displays 6
document.write("<P>The index of 'new' from the end is " +
anyString.lastIndexOf("new"))
In LiveWire, you can display the same values by calling the write function instead of using document.write.
See also
charAt, lastIndexOf methods
isNaN
Function. On Unix platforms, evaluates an argument to determine if it is "NaN" (not a number).
Syntax
isNaN(testValue)
Parameters
testValue is the value you want to evaluate.
Description
isNaN is a built-in JavaScript function. It is not a method associated with any object, but is part of the language itself. isNaN is available on Solaris and Irix platforms only.
On platforms that support NaN, the parseFloat and parseInt functions return "NaN" when they evaluate a value that is not a number. The isNaN returns true if passed "NaN," and false otherwise.
Examples
The following example evaluates floatValue to determine if it is a number and then calls a procedure accordingly:
floatValue=parseFloat(toFloat)
if isNaN(floatValue) {
notFloat()
} else {
isFloat()
}
See also
parseFloat, parseInt functions
italics
Method. Causes a string to be italic, as if it were in an I tag.
Syntax
stringName.italics()
Parameters
stringName is any string or a property of an existing object.
Method of
string
Description
Use the italics 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 could generate this HTML by calling the write function instead of using document.write.
See also
blink, bold, strike methods
lastIndexOf
Method. Returns the index within the calling string object of the last occurrence of the specified value. The calling string is searched backward, starting at fromIndex.
Syntax
stringName.lastIndexOf(searchValue, [fromIndex])
Parameters
stringName is any string or a property of an existing object.
searchValue is a string or a property of an existing object, representing the value to search for.
fromIndex is the location within the calling string to start the search from. It can be 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 you do not specify a value for fromIndex, JavaScript assumes stringName.length - 1 (the end of the string) by default. If searchValue is not found, JavaScript returns -1.
Examples
The following example uses indexOf and lastIndexOf to locate values in the string "Brave new world."
var anyString="Brave new world"
//Displays 8
document.write("<P>The index of the first w from the beginning is " +
anyString.indexOf("w"))
//Displays 10
document.write("<P>The index of the first w from the end is " +
anyString.lastIndexOf("w"))
//Displays 6
document.write("<P>The index of 'new' from the beginning is " +
anyString.indexOf("new"))
//Displays 6
document.write("<P>The index of 'new' from the end is " +
anyString.lastIndexOf("new"))
In LiveWire, you can display the same output by calling the write function instead of using document.write.
See also
charAt, indexOf methods
lastModified
Property. A string representing the date that a document was last modified.
Syntax
document.lastModified
Property of
document
Description
lastModified is a read-only property.
Examples
In the following example, the lastModified property is used in a SCRIPT tag at the end of an HTML file to display the modification date of the page:
document.write("This page updated on " + document.lastModified)
length
Property. An integer that specifies a length-related feature of the calling object or array.
Syntax
When used with objects:
1. formName.length
2. frameReference.length
3. history.length
4. radioName.length
5. selectName.length
6. stringName.length
7. windowReference.length
When used with array properties:
8. anchors.length
9. arguments.length
10. elements.length
11. forms.length
12. frameReference.frames.length
13. windowReference.frames.length
14. links.length
15. selectName.options.length
Parameters
formName is either the name of a form or an element in the forms array.
frameReference is either the value of the NAME attribute of a frame or an element in the frames array.
radioName is either the value of the NAME attribute of a radio 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.
stringName is any string or a property of an existing object.
windowReference is a valid way of referring to a window, as described in the window object.
Property of
Description
The length property is an integer that specifies one of the following:
Examples
In the following example, the getChoice function uses the length property to iterate over every element in the musicType array. musicType is a select element on the musicForm form.
function getChoice() {
for (var i = 0; i < document.musicForm.musicType.length; i++) {
if (document.musicForm.musicType.options[i].selected == true) {
return document.musicForm.musicType.options[i].text
}
}
}
The following example displays 8 in an Alert dialog box:
var x="Netscape"
alert("The string length is " + x.length)
link method
Method. Creates an HTML hypertext link that requests another URL.
Syntax
linkText.link(hrefAttribute)
Parameters
linkText is any string or a property of an existing object. This represents the text that will be displayed in the link.
hrefAttribute is any string that specifies the HREF attribute of the A tag; it should be a valid URL (relative or absolute).
Method of
string
Description
Use the link method to programmatically create a hypertext link, and then call write or writeln to display the link in a document. In LiveWire, use the write function to display the string.
Links created with the link method become elements in the links array. See the link object for information about the links array.
Examples
The following example displays the word "Netscape" as a hypertext link that returns the user to the Netscape home page:
var hotText="Netscape"
var URL="http://www.netscape.com"
document.write("Click to return to " + hotText.link(URL))
The previous example produces the same output as the following HTML:
Click to return to <A HREF="http://www.netscape.com">Netscape</A>
In LiveWire, you can generate this HTML by calling the write function instead of using document.write.
See also
anchor object
link object
Object. A piece of text or an image identified as a hypertext link. When the user clicks the link text or image, the link hypertext reference is loaded into its target window.
HTML syntax
To define a link, use standard HTML syntax with the addition of the onClick and onMouseOver event handlers:
<A HREF=locationOrURL
[NAME="anchorName"]
[TARGET="windowName"]
[onClick="handlerText"]
[onMouseOver="handlerText"]>
linkText
</A>
You can also define a link using the link method.
HTML attributes
HREF=locationOrURL identifies a destination anchor or URL. See the location object for a description of the URL components.
NAME="anchorName" is used only if the link is also an anchor. It specifies a name for the anchor that then becomes an available hypertext target within the current document. See the anchor object for details.
TARGET="windowName" specifies the frame or window that the link is loaded into. windowName can be an existing window; it can be a frame name specified in a FRAMESET tag; or it can be one of the literal frame names _top, _parent, _self, or _blank. It cannot be a JavaScript expression (for example, it cannot be parent.frameName or windowName.frameName).
linkText is the text or HTML source that the user sees as a hypertext link to the URL.
Syntax
To use a link object's properties:
document.links[index].propertyName
Parameters
index is an integer representing a link object.
propertyName is one of the properties listed below.
Property of
document
Description
Each link object is a location object and has the same properties as a location object.
If a link object is also an anchor object, the object has entries in both the anchors and links arrays.
When a user clicks a link object and navigates to the destination document (specified by HREF=locationOrURL), the destination document's referrer property contains the URL of the source document. Evaluate the referrer property from the destination document.
The links array
You can reference the link objects in your code by using the links array. This array contains an entry for each link object (A HREF="" tag) in a document in source order. For example, if a document contains three link objects, these links are reflected as document.links[0], document.links[1], and document.links[2].
To use the links array:
1. document.links[index]
2. document.links.length
index is an integer representing a link in a document.
To obtain the number of links in a document, use the length property: document.links.length.
Elements in the links array are read-only. For example, the statement document.links[0]="link1" has no effect.
Properties
The link object has the following properties:
The links array has the following property:
| Property | Description |
|---|---|
| length | Reflects the number of links in a document |
Methods
None
Event handlers
Examples
Example 1. The following example creates a hypertext link to an anchor named javascript_intro:
<A HREF="#javascript_intro">Introduction to JavaScript</A>
Example 2. The following example creates a hypertext link to an anchor named numbers in the file doc3.html in the window window2. If window2 does not exist, it is created.
<LI><A HREF=doc3.html#numbers TARGET="window2">Numbers</A>
Example 3. The following example takes the user back x entries in the history list:
<A HREF="javascript:history.go(-1 * x)">Click here</A>
Example 4. The following example creates a hypertext link to a URL. The user can use the set of radio buttons to choose between three URLs. The link's onClick event handler sets the URL (the link's href property) based on the selected radio button. The link also has an onMouseOver event handler that changes the window's status property. As the example shows, you must return true to set the window.status property in the onMouseOver event handler.
<SCRIPT>
var destHREF="http://www.netscape.com/"
</SCRIPT>
<FORM NAME="form1">
<B>Choose a destination from the following list, then click "Click me" below.</B>
<BR><INPUT TYPE="radio" NAME="destination" VALUE="netscape"
onClick="destHREF='http://www.netscape.com/'"> Netscape home page
<BR><INPUT TYPE="radio" NAME="destination" VALUE="sun"
onClick="destHREF='http://www.sun.com/'"> Sun home page
<BR><INPUT TYPE="radio" NAME="destination" VALUE="rfc1867"
onClick="destHREF='http://www.ics.uci.edu/pub/ietf/html/rfc1867.txt'"> RFC 1867
<P><A HREF=""
onMouseOver="window.status='Click this if you dare!'; return true"
onClick="this.href=destHREF">
<B>Click me</B></A>
</FORM>
Example 5: links array. The following example opens the Netscape home page in the newWindow window. The linkGetter function uses the links array to display the value of each of its links.
newWindow=window.open("http://www.netscape.com")
function linkGetter() {
msgWindow=window.open("")
for (var i = 0; i < newWindow.document.links.length; i++) {
msgWindow.document.write(newWindow.document.links[i] + "<BR>")
}
}
See also
anchor object, link method
linkColor
Property. A string specifying the color of the document hyperlinks.
Syntax
document.linkColor
Property of
document
Description
The linkColor 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 LINK 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 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 document links to aqua using a string literal:
document.linkColor="aqua"
The following example sets the color of document links to aqua using a hexadecimal triplet:
document.linkColor="00FFFF"
See also
alinkColor, bgColor, fgColor, vlinkColor properties
links
Property. An array of objects corresponding to link objects in source order. See the link object.
LN2
Property. The natural logarithm of two, approximately 0.693.
Syntax
Math.LN2
Property of
Math
Description
Because LN2 is a constant, it is a read-only property of Math.
Examples
The following function returns the natural log of two:
function getNatLog2() {
return Math.LN2
}
See also
E, LN10, LOG2E, LOG10E, PI, SQRT1_2, SQRT2 properties
LN10
Property. The natural logarithm of ten, approximately 2.302.
Syntax
Math.LN10
Property of
Math
Description
Because LN10 is a constant, it is a read-only property of Math.
Examples
The following function returns the natural log of ten:
function getNatLog10() {
return Math.LN10
}
See also
E, LN2, LOG2E, LOG10E, PI, SQRT1_2, SQRT2 properties
location object
Object. Contains information on the current URL.
Syntax
To use a location object:
[windowReference.]location[.propertyName]
Parameters
windowReference is a variable windowVar from a window definition (see the window object), or one of the synonyms top or parent.
propertyName is one of the properties listed below. Omitting the property name is equivalent to specifying the href property (the complete URL).
Property of
window object
Description
The location object represents a complete URL. Each property of the location object represents a different portion of the URL.
The following diagram of a URL shows the relationships between the location properties:
protocol//host:port/pathname#hash?search
For example:
http://www.netscape.com/assist/extensions.html#topic1?x=7&y=2
Following is a description of each part of the URL diagram:
The location object has two other properties not shown in the diagram above:
.location.propertyName, the location object represents the location of the specified window.
Syntax for common URL types
When you specify a URL, you can use standard URL formats and JavaScript statements. The following list shows the syntax for specifying some of the most common types of URLs.
The javascript: protocol evaluates the expression after the colon (:), if there is one, and loads a page containing the string value of the expression, unless it is undefined. If the expression evaluates to undefined, no new page loads.
The about: protocol provides information on Navigator and has the following syntax:
about:[cache|plugins]
Properties
The location object has the following properties:
Methods
None
Event handlers
None
Examples
Example 1. The following two statements are equivalent and set the URL of the current window to the Netscape home page:
window.location.href="http://www.netscape.com/"
window.location="http://www.netscape.com/"
Example 2. The following statement sets the URL of a frame named frame2 to the Sun home page:
parent.frame2.location.href="http://www.sun.com/"
See also the example for the anchor object.
See also
history object, URL property
log
Method. Returns the natural logarithm (base e) of a number.
Syntax
Math.log(number)
Parameters
number is any positive numeric expression or a property of an existing object.
Method of
Math
Description
If the value of number is outside the suggested range, the return value is always -1.797693134862316e+308.
Examples
The following function returns the natural log of the variable x:
function getLog(x) {
return Math.log(x)
}
If you pass getLog the value ten, it returns 2.302585092994046; if you pass it the value zero, it returns -1.797693134862316e+308 because zero is out of range.
See also
exp, pow methods
LOG2E
Property. The base 2 logarithm of e (approximately 1.442).
Syntax
Math.LOG2E
Property of
Math
Description
Because LOG2E is a constant, it is a read-only property of Math.
Examples
The following function returns the base 2 logarithm of E:
function getLog2e() {
return Math.LOG2E
}
See also
E, LN2, LN10, LOG10E, PI, SQRT1_2, SQRT2 properties
LOG10E
Property. The base 10 logarithm of e (approximately 0.434).
Syntax
Math.LOG10E
Property of
Math
Description
Because LOG10E is a constant, it is a read-only property of Math.
Examples
The following function returns the base 10 logarithm of E:
function getLog10e() {
return Math.LOG10E
}
See also
E, LN2, LN10, LOG2E, PI, SQRT1_2, SQRT2 properties