1. links[index].hash 2. location.hash 3. areaName.hash
areaName is the value of the NAME attribute of an Area object.
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.
Setting the hash property navigates to the named anchor without reloading the document. This differs from the way a document is loaded when other location properties are set (see "How documents are loaded when location is set").
In event handlers, you must specify window.location.hash instead of simply using location.hash. Due to the scoping of static objects in JavaScript, a call to location without specifying an object name is equivalent to document.location, which is a synonym for document.URL.
See RFC 1738 for complete information about the hash.
imageName.height
height is a read-only property.
function showImageSize(theImage) {
alert('height=' + theImage.height+
'; width=' + theImage.width +
'; hspace=' + theImage.hspace +
'; vspace=' + theImage.vspace)
}
<INPUT TYPE="hidden" NAME="hiddenName" [VALUE="textValue"]>
VALUE="textValue" specifies the initial value of the Hidden object.
1. hiddenName.propertyName 2. formName.elements[index].propertyName
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 or the name of a Hidden object as specified by the NAME attribute.
propertyName is one of the properties listed below.
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.
| Property | Description |
|---|---|
| name | Reflects the NAME attribute |
| form property | Specifies the form containing the Hidden object |
| type | Reflects the TYPE attribute |
| value | Reflects the current value of the Hidden object |
<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>
1. history.propertyName 2. history.methodName(parameters) 3. [windowReference.]history[index]
methodName is one of the methods listed below.
windowReference is a valid way of referring to a window, as described in the window object.
index is an integer representing an entry in the history list.
To change a window's current URL without generating a history entry, you can use the replace method. This replaces the current page with a new one without generating a history entry. See the replace method.
1. history[index] 2. history.lengthindex is an integer representing an entry in the history list.
To obtain the number of entries in the history list, use the length property: history.length.
Elements in the history array are read-only. For example, the statement history[0]="http://home.netscape.com" has no effect.
If you access the history array without specifying an array element, Navigator returns a string of HTML which displays a table of URLs, each of which is a hyperlink.
| Property | Description |
|---|---|
| current | Specifies the URL of the current history entry |
| length | Reflects the number of entries in the history list |
| next | Specifies the URL of the next history entry |
| previous | Specifies the URL of the previous history entry |
The history array has the following properties:
| Property | Description |
|---|---|
| length | Reflects the number of history entries in the window |
|
|
|
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()Example 6. The following code determines whether the first entry in the history array contains the string "NETSCAPE". If it does, the function myFunction is called.
if (history[0].indexOf("NETSCAPE") != -1) {
myFunction(history[0])
}
Example 7. The following
example displays the entire history list:
document.writeln("<B>history is</B> " + history)
This code displays output similar
to the following:
history is
Welcome to Netscape http://home.netscape.com/
Sun Microsystems http://www.sun.com/
SlugVideo at the Dream Inn http://sapphire.cse.ucsc.edu/SlugVideo/dream-inn.html
Bad Dog Chronicles http://www.supernet.net/~dugbrown/
1. links[index].host 2. location.host 3. areaName.host
areaName is the value of the NAME attribute of an Area object.
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.
In event handlers, you must specify window.location.host instead of simply using location.host. Due to the scoping of static objects in JavaScript, a call to location without specifying an object name is equivalent to document.location, which is a synonym for document.URL.
See Section 3.1 of RFC 1738 for complete information about the hostname and port.
1. links[index].hostname 2. location.hostname 3. areaName.hostname
areaName is the value of the NAME attribute of an Area object.
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.
In event handlers, you must specify window.location.hostname instead of simply using location.hostname. Due to the scoping of static objects in JavaScript, a call to location without specifying an object name is equivalent to document.location, which is a synonym for document.URL.
See Section 3.1 of RFC 1738 for complete information about the hostname.
1. links[index].href 2. location.href 3. areaName.href
areaName is the value of the NAME attribute of an Area object.
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://home.netscape.com/" window.location="http://home.netscape.com/"In event handlers, you must specify window.location.href instead of simply using location.href. Due to the scoping of static objects in JavaScript, a call to location without specifying an object name is equivalent to document.location, which is a synonym for document.URL.
See RFC 1738 for complete information about the URL.
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 =
imageName.hspace
hspace is a read-only property.
<IMG [NAME="imageName"] SRC="Location" [LOWSRC="Location"] [HEIGHT="Pixels"|"Value"%] [WIDTH="Pixels"|"Value"%] [HSPACE="Pixels"] [VSPACE="Pixels"] [BORDER="Pixels"] [ALIGN="left"|"right"| "top"|"absmiddle"|"absbottom"| "texttop"|"middle"|"baseline"|"bottom"] [ISMAP] [USEMAP="#MapName"] [onAbort="handlerText"] [onError="handlerText"] [onLoad="handlerText"]>
SRC="Location" specifies the URL of the image to be displayed in the document. You can access this value using the src property.
LOWSRC="Location" specifies the URL of a low-resolution version of the image to be displayed in the document. Navigator loads this smaller image and then replaces it with the larger image specified by SRC. You can access this value using the lowsrc property.
HEIGHT="Pixels"|"Value"% specifies the height of the image either in pixels or as a percentage of the window height. If necessary, Navigator scales the image to fit the space specified by this attribute. You can access this value using the height property.
WIDTH="Pixels"|"Value"% specifies the width of the image either in pixels or as a percentage of the window width. If necessary, Navigator scales the image to fit the space specified by this attribute. You can access this value using the width property.
HSPACE="Pixels" specifies a margin in pixels between the left and right edges of the image and the surrounding text. This attribute applies only to images that use "left" or "right" as the value of the ALIGN attribute. You can access this value using the hspace property.
VSPACE="Pixels" specifies a margin in pixels between the top and bottom edges of the image and the surrounding text. This attribute applies only to images that use "left" or "right" as the value of the ALIGN attribute. You can access this value using the vspace property.
BORDER="Pixels" specifies the width, in pixels, of an image border. You can suppress the border by setting its value to 0; however, if you suppress the border of an image that appears within an anchor, users will not see a colored border indicating that the image is a hyperlink. You can access this value using the border property.
ALIGN specifies the alignment of the image in relation to the surrounding text. Images that are aligned as "left" or "right" float into the next available space on the left or right side of the page, and cause text to wrap around them. Other ALIGN values place the image in a line of text and do not cause the text to wrap. If omitted, "bottom" is used.
ISMAP specifies the image as a server-side image map.
USEMAP="#MapName" specifies the image as a client-side image map. This attribute specifies the # symbol followed by the name of the map. For example, USEMAP="#areamap".
imageName = new Image([width, height])To use an Image object's properties:
1. imageName.propertyName 2. document.images[index].propertyName 3. formName.elements[index].propertyNameTo define an event handler for an Image object created with the Image() constructor:
1. imageName.onabort = handlerFunction 2. imageName.onerror = handlerFunction 3. imageName.onload = handlerFunction
width is the image width, in pixels.
height is the image height, in pixels.
formName is either the value of the NAME attribute of a Form object or an element in the forms array.
index, when used with the images array is an integer representing an Image object or the name of an Image object as specified by the NAME attribute. index, when used with the elements array, is an integer representing an Image object on a form.
propertyName is one of the properties listed below.
handlerFunction is the keyword null, the name of a function, or a variable or property that contains null or a valid function reference.
You can use JavaScript to create an animation with an Image object by repeatedly setting the src property, as shown in Example 4 below. JavaScript animation is slower than GIF animation, because with GIF animation the entire animation is in one file; with JavaScript animation, each frame is in a separate file, and each file must be loaded across the network (host contacted and data transferred).
Image objects do not have onClick, onMouseOut, and onMouseOver event handlers. However, if you define an Area object for the image or place the <IMG> tag within a Link object, you can use the Area or Link object's event handlers. See the Link object.
myImage = new Image() myImage.src = "seaotter.gif" ... document.images[0].src = myImage.srcThe resulting image will be obtained from cache, rather than loaded over the network, assuming that sufficient time has elapsed to load and decode the entire image. You can use this technique to create smooth animations, or you could display one of several images based on form input.
1. document.images[index] 2. document.images.lengthindex is an integer representing an image in a document or the name of an Image object as specified by the NAME attribute.
To obtain the number of images in a document, use the length property: document.images.length.
Elements in the images array are read-only. For example, the statement document.images[0]="logo.gif" has no effect.
| Property | Description |
|---|---|
| border | Reflects the BORDER attribute |
| complete | Boolean value indicating whether Navigator has completed its attempt to load the image |
| height | Reflects the HEIGHT attribute |
| hspace | Reflects the HSPACE attribute |
| lowsrc | Reflects the LOWSRC attribute |
| name | Reflects the NAME attribute |
| prototype | Lets you add a properties to an Image object. |
| src | Reflects the SRC attribute |
| vspace | Reflects the VSPACE attribute |
| width | Reflects the WIDTH attribute |
Note
The border, hspace, name, and vspace properties are not meaningful for images created with the Image() constructor.The images array has the following properties:
| Property | Description |
|---|---|
| length | Reflects the number of images in a document |
<IMG NAME="aircraft" SRC="f15e.gif" ALIGN="left" VSPACE="10">The following code refers to the image:
document.aircraft.src='f15e.gif'When you refer to an image by its name, you must include the form name if the image is on a form. The following code refers to the image if it is on a form:
document.myForm.aircraft.src='f15e.gif'Example 2: Create an image with the Image() constructor. The following example creates an Image object, myImage, that is 70 pixels wide and 50 pixels high. If the source URL, seaotter.gif, does not have dimensions of 70x50 pixels, it is scaled to that size.
myImage = new Image(70, 50) myImage.src = "seaotter.gif"If you omit the width and height arguments from the Image() constructor, myImage is created with dimensions equal to that of the image named in the source URL.
myImage = new Image() myImage.src = "seaotter.gif"Example 3: Display an image based on form input. In the following example, the user selects which image is displayed. The user orders a shirt by filling out a form. The image displayed depends on the shirt color and size that the user chooses. All possible image choices are pre-loaded to speed response time. When the user clicks the button to order the shirt, the allShirts function displays the images of all the shirts.
<SCRIPT>
shirts = new Array()
shirts[0] = "R-S"
shirts[1] = "R-M"
shirts[2] = "R-L"
shirts[3] = "W-S"
shirts[4] = "W-M"
shirts[5] = "W-L"
shirts[6] = "B-S"
shirts[7] = "B-M"
shirts[8] = "B-L"
doneThis = 0
shirtImg = new Array()
// Preload shirt images
for(idx=0; idx < 9; idx++) {
shirtImg[idx] = new Image()
shirtImg[idx].src = "shirt-" + shirts[idx] + ".gif"
}
function changeShirt(form)
{
shirtColor = form.color.options[form.color.selectedIndex].text
shirtSize = form.size.options[form.size.selectedIndex].text
newSrc = "shirt-" + shirtColor.charAt(0) + "-" + shirtSize.charAt(0) + ".gif"
document.shirt.src = newSrc
}
function allShirts()
{
document.shirt.src = shirtImg[doneThis].src
doneThis++
if(doneThis != 9)setTimeout("allShirts()", 500)
else doneThis = 0
return
}
</SCRIPT>
<FONT SIZE=+2><B>Netscape Polo Shirts!</FONT></B>
<TABLE CELLSPACING=20 BORDER=0>
<TR>
<TD><IMG name="shirt" SRC="shirt-W-L.gif"></TD>
<TD>
<FORM>
<B>Color</B>
<SELECT SIZE=3 NAME="color" onChange="changeShirt(this.form)">
<OPTION> Red
<OPTION SELECTED> White
<OPTION> Blue
</SELECT>
<P>
<B>Size</B>
<SELECT SIZE=3 NAME="size" onChange="changeShirt(this.form)">
<OPTION> Small
<OPTION> Medium
<OPTION SELECTED> Large
</SELECT>
<P><INPUT type="button" name="buy" value="Buy This Shirt!"
onClick="allShirts()">
</FORM>
</TD>
</TR>
</TABLE>
Example 4: JavaScript animation.
The following example uses JavaScript to create an animation with an Image
object by repeatedly changing the value the src property. The script
begins by preloading the 10 images that make up the animation (image1.gif,
image2.gif, image3.gif, and so on). When the Image
object is placed on the document with the <IMG> tag, image1.gif
is displayed and the onLoad event handler starts the animation by calling
the animate function. Notice that the animate function does
not call itself after changing the src property of the Image
object. This is because when the src property changes, the image's
onLoad event handler is triggered and the animate function is called.
<SCRIPT>
delay = 100
imageNum = 1
// Preload animation images
theImages = new Array()
for(i = 1; i < 11; i++) {
theImages[i] = new Image()
theImages[i].src = "image" + i + ".gif"
}
function animate() {
document.animation.src = theImages[imageNum].src
imageNum++
if(imageNum > 10) {
imageNum = 1
}
}
function slower() {
delay+=10
if(delay > 4000) delay = 4000
}
function faster() {
delay-=10
if(delay < 0) delay = 0
}
</SCRIPT>
<BODY BGCOLOR="white">
<IMG NAME="animation" SRC="image1.gif" ALT="[Animation]"
onLoad="setTimeout('animate()', delay)">
<FORM>
<INPUT TYPE="button" Value="Slower" onClick="slower()">
<INPUT TYPE="button" Value="Faster" onClick="faster()">
</FORM>
</BODY>
See also the examples for the
onAbort, onError,
and onLoad event handlers.
1. selectName.options[indexValue].index 2. optionName.index
indexValue is an integer representing an option in a Select object.
optionName is the name of a Select object option created using the Option() constructor.
stringName.indexOf(searchValue, [fromIndex])
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.
If you do not specify a value for fromIndex, JavaScript assumes zero by default. If searchValue is not found, JavaScript returns -1.
If stringName contains an empty string (""), indexOf returns an empty string.
The indexOf method is case sensitive. For example, the following expression returns -1:
"Blue Whale".indexOf("blue")
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"))
Example 2. The following
example defines two string variables. The variables contain the same string
except that the second string contains uppercase letters. The first writeln
method displays 19. But because the indexOf method is case sensitive,
the string "cheddar" is not found in myCapString, so the second
writeln method displays -1.
myString="brie, pepper jack, cheddar"
myCapString="Brie, Pepper Jack, Cheddar"
document.writeln('myString.indexOf("cheddar") is ' +
myString.indexOf("cheddar"))
document.writeln('<P>myCapString.indexOf("cheddar") is ' +
myCapString.indexOf("cheddar"))
isNaN(testValue)
On platforms that support NaN, the parseFloat and parseInt functions return "NaN" when they evaluate a value that is not a number. isNaN returns true if passed "NaN," and false otherwise.
floatValue=parseFloat(toFloat)
if (isNaN(floatValue)) {
notFloat()
} else {
isFloat()
}
stringName.italics()
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>
navigator.javaEnabled()
if (navigator.javaEnabled()) {
function1()
}
else function2()
arrayName.join(separator)
separator specifies a string to separate each element of the array. The separator is converted to a string if necessary. If omitted, the array elements are separated with a comma (,).
a = new Array("Wind","Rain","Fire")
document.write(a.join() +"<BR>")
document.write(a.join(", ") +"<BR>")
document.write(a.join(" + ") +"<BR>")
This code produces the following
output:
Wind,Rain,Fire Wind, Rain, Fire Wind + Rain + Fire
stringName.lastIndexOf(searchValue, [fromIndex])
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.
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.
The lastIndexOf method is case sensitive. For example, the following expression returns -1:
"Blue Whale, Killer Whale".lastIndexOf("blue")
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"))
document.lastModified
The last modified date is not a required portion of the header, and some servers do not supply it. If the server does not return the last modified information, JavaScript receives a zero, which it displays as January 1, 1970 GMT. The following code checks the date returned by lastModified and prints out a value that corresponds to unknown.
lastmod = document.lastModified // get string of last modified date
lastmoddate = Date.parse(lastmod) // convert modified string to date
if(lastmoddate == 0){ // unknown date (or January 1,
// 1970 GMT)
document.writeln("Lastmodified: Unknown")
} else {
document.writeln("LastModified: " + lastmod)
}
lastModified is a read-only
property.
document.write("This page updated on " + document.lastModified)
1. formName.length 2. frameReference.length 3. history.length 4. radioName.length 5. selectName.length 6. stringName.length 7. windowReference.length 8. arrayName.lengthWhen used with array properties:
9. anchors.length 10. applets.length 11. arguments.length 12. elements.length 13. embeds.length 14. forms.length 15. frames.length 16. history.length 17. images.length 18. links.length 19. mimeTypes.length 20. plugins.length 21. plugins[mimeTypeIndex].length 22. selectName.options.length
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.
arrayName is the name of an Array object.
mimeTypeIndex is either an integer representing a MIME type supported by the plug-in or a string containing the type of a MimeType object (from the type property).
For a null string, length is zero. For a Select object, the values returned by form 5 and form 22 of the syntax are the same. For a window containing frames, the values returned by form 7 and form 15 of the syntax are the same. For a Form object, the values returned by form 1 and form 12 of the syntax are the same. For a frame containing frames, the values returned by form 2 and form 15 of the syntax are the same.
For arrays, you can set the length property to truncate an array at any time. You cannot extend an array; for example, if you set length to 3 when it is currently 2, the array will still contain only 2 elements. For information on other ways to change the length of an array, see the Array object.
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)
The following example shortens
the array statesUS to a length of 50 if the current length is greater
than 50.
if (statesUS.length > 50) {
statesUS.length=50
alert("The U.S. has only 50 states. New length is " + statesUS.length)
}
linkText.link(hrefAttribute)
hrefAttribute is any string that specifies the HREF attribute of the <A> tag; it should be a valid URL (relative or absolute).
Links created with the link method become elements in the links array. See the Link object for information about the links array.
var hotText="Netscape"
var URL="http://home.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://home.netscape.com">Netscape</A>
<A HREF=locationOrURL [NAME="anchorName"] [TARGET="windowName"] [onClick="handlerText"] [onMouseOut="handlerText"]> [onMouseOver="handlerText"]> linkText </A>You can also define a link using the link method.
To define an area, use standard HTML syntax with the addition of JavaScript event handlers:
<MAP NAME="mapName"> <AREA [NAME="areaName"] COORDS="x1,y1,x2,y2,..."|"x-center,y-center,radius" HREF="locationOrURL" [SHAPE="rect"|"poly"|"circle"|"default"] [TARGET="windowName"] [onMouseOut="handlerText"] [onMouseOver="handlerText"]> </MAP>
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.
NAME="mapName" specifies the name of the map. You can specify this map name in the USEMAP attribute of the <IMG> tag.
AREA defines an area of an image as an image map.
NAME="areaName" specifies the name of the Area object. This attribute is not reflected in JavaScript (you cannot refer to an Area object by name).
COORDS specifies the coordinates of the image map.
SHAPE specifies the shape of the map. "default" specifies a region as the default. If omitted, "rect" is used.
document.links[index].propertyName
propertyName is one of the properties listed below.
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.
You can use a Link object to execute a JavaScript function rather than link to a hypertext reference by specifying the javascript: URL protocol for the link's HREF attribute. You might want to do this if the link surrounds an Image object and you want to execute JavaScript code when the image is clicked. Or you might want to use a link instead of a button to execute JavaScript code.
For example, when a user clicks the following links, the slower and faster functions execute:
<A HREF="javascript:slower()">Slower</A> <A HREF="javascript:faster()">Faster</A>You can use a Link object to do nothing rather than link to a hypertext reference by specifying the javascript:void(0) URL protocol for the link's HREF attribute. You might want to do this if the link surrounds an Image object and you want to use the link's event handlers with the image. When a user clicks the following link or image, nothing happens:
<A HREF="javascript:void(0)">Click here to do nothing</A> <A HREF="javascript:void(0)"> <IMG SRC="images\globe.gif" ALIGN="top" HEIGHT="50" WIDTH="50"> </A>
The HREF attribute is required for Area objects that use the onMouseOut or onMouseOver event handlers. However, if you create an Area for an image and do not want the image to link to a hypertext reference when clicked, specify a JavaScript function in the area's HREF attribute by using the javascript: URL protocol. For example, if a user clicks the following Area object, the function onTop executes.
<MAP NAME="worldMap"> <AREA NAME="topWorld" COORDS="0,0,50,25" HREF="javascript:onTop()" onMouseOver="self.status='You are on top of the world';return true" onMouseOut="self.status='You have left the top of the world';return true"> </MAP>If you want an area's link to do nothing, use javascript:void(0) in the HREF attribute. When the user clicks the following Area object, nothing happens:
<MAP NAME="worldMap"> <AREA NAME="topWorld" COORDS="0,0,50,25" HREF="javascript:void(0)" onMouseOver="self.status='You are on top of the world';return true" onMouseOut="self.status='You have left the top of the world';return true"> </MAP>
1. document.links[index] 2. document.links.lengthindex is an integer representing a link in a document or the name of a Link object as specified by the NAME attribute.
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.
| Property | Description |
|---|---|
| hash | Specifies an anchor name in the URL |
| host | Specifies the host and domain name, or IP address, of a network host |
| hostname | Specifies the host:port portion of the URL |
| href | Specifies the entire URL |
| pathname | Specifies the url-path portion of the URL |
| port | Specifies the communications port that the server uses for communications |
| protocol | Specifies the beginning of the URL, including the colon |
| search | Specifies a query |
| target | Reflects the TARGET attribute |
The links array has the following property:
| Property | Description |
|---|---|
| length | Reflects the number of links in a document |
<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://home.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://home.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. In the following example, the linkGetter function uses the links array to display the value of each link in the current document. The example also defines several links and a button for running linkGetter.
function linkGetter() {
msgWindow=window.open("","msg","width=400,height=400")
msgWindow.document.write("links.length is " +
document.links.length + "<BR>")
for (var i = 0; i < document.links.length; i++) {
msgWindow.document.write(document.links[i] + "<BR>")
}
}
<A HREF="http://home.netscape.com">Netscape Home Page</A>
<A HREF="http://www.catalog.com/fwcfc/">China Adoptions</A>
<A HREF="http://www.supernet.net/~dugbrown/">Bad Dog Chronicles</A>
<A HREF="http://www.best.com/~doghouse/homecnt.shtml">Lab Rescue</A>
<P>
<INPUT TYPE="button" VALUE="Display links"
onClick="linkGetter()">
Example 6: Area object with
onMouseOver and onMouseOut event handlers. The following example displays
an image, globe.gif. The image uses an image map that defines
areas for the top half and the bottom half of the image. The onMouseOver
and onMouseOut event handlers display different status bar messages depending
on whether the mouse passes over or leaves the top half or bottom half
of the image. The HREF attribute is required when using the onMouseOver
and onMouseOut event handlers, but in this example the image does not need
a hypertext link, so the HREF attribute executes javascript:void(0),
which does nothing (see "void" for more
information).
<MAP NAME="worldMap"> <AREA NAME="topWorld" COORDS="0,0,50,25" HREF="javascript:void(0)" onMouseOver="self.status='You are on top of the world';return true" onMouseOut="self.status='You have left the top of the world';return true"> <AREA NAME="bottomWorld" COORDS="0,25,50,50" HREF="javascript:void(0)" onMouseOver="self.status='You are on the bottom of the world';return true" onMouseOut="self.status='You have left the bottom of the world';return true"> </MAP> <IMG SRC="images\globe.gif" ALIGN="top" HEIGHT="50" WIDTH="50" USEMAP="#worldMap">Example 7: Refer to Area object with links array. The following code refers to the href property of the first Area object shown in Example 1.
document.links[0].hrefExample 8: Simulate an Area object's onClick using the HREF attribute. The following example uses an Area object's HREF attribute to execute a JavaScript function. The image displayed, colors.gif, shows two sample colors. The top half of the image is the color "antiquewhite", and the bottom half is "white". When the user clicks the top or bottom half of the image, the function setBGColor changes the document's background color to the color shown in the image.
<SCRIPT>
function setBGColor(theColor) {
document.bgColor=theColor
}
</SCRIPT>
Click the color you want for this document's background color
<MAP NAME="colorMap">
<AREA NAME="topColor" COORDS="0,0,50,25" HREF="javascript:setBGColor('antiquewhite')">
<AREA NAME="bottomColor" COORDS="0,25,50,50" HREF="javascript:setBGColor('white')">
</MAP>
<IMG SRC="images\colors.gif" ALIGN="top" HEIGHT="50" WIDTH="50" USEMAP="#colorMap">
document.linkColor
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."
document.linkColor="aqua"The following example sets the color of document links to aqua using a hexadecimal triplet:
document.linkColor="00FFFF"
Math.LN2
function getNatLog2() {
return Math.LN2
}
Math.LN10
function getNatLog10() {
return Math.LN10
}
[windowReference.]location[.propertyName] [windowReference.]location.methodName(parameters)
propertyName is one of the properties listed below. Omitting the property name is equivalent to specifying the href property (the complete URL).
methodName is one of the methods listed below.
The following diagram of a URL shows the relationships between the location properties:
protocol//host:port/pathname#hash?searchFor example:
http://home.netscape.com/assist/extensions.html#topic1?x=7&y=2Following is a description of each part of the URL diagram:
The location object
has two other properties not shown in the diagram above:
window.location.href="http://home.netscape.com/" window.location="http://home.netscape.com/"The location object is contained by the window object and is within its scope. If you reference a location object without specifying a window, the location object represents the current location. If you reference a location object and specify a window name, for example, windowReference.location
In event handlers, you must specify window.location instead of simply using location. Due to the scoping of static objects in JavaScript, a call to location without specifying an object name is equivalent to document.location, which is a synonym for document.URL.
Do not use location as a property of the document object; use the document.URL property instead. The document.location property, which is a synonym for document.URL, will be removed in a future release.
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 (by calling a void function, for example javascript:void(0)), no new page loads. Note that loading a new page over your script's page clears the page's variables, functions, and so on.
The view-source: protocol displays HTML code that was generated with JavaScript write and writeln methods. For information on printing and saving generated HTML, see the write method.
The about: protocol provides information on Navigator and has the following syntax:
about:[cache|plugins]
| Property | Description |
|---|---|
| hash | Specifies an anchor name in the URL |
| host | Specifies the host and domain name, or IP address, of a network host |
| hostname | specifies the host:port portion of the URL |
| href | Specifies the entire URL |
| pathname | Specifies the url-path portion of the URL |
| port | Specifies the communications port that the server uses for communications |
| protocol | Specifies the beginning of the URL, including the colon |
| search | Specifies a query |
|
|
|
window.location.href="http://home.netscape.com/" window.location="http://home.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 examples for the Anchor object.
Math.log(number)
function getLog(x) {
return Math.log(x)
}
If you pass getLog the
value 10, it returns 2.302585092994046; if you pass it the value zero,
it returns -1.797693134862316e+308 because zero is out of range.
Math.LOG2E
function getLog2e() {
return Math.LOG2E
}
Math.LOG10E
function getLog10e() {
return Math.LOG10E
}
imageName.lowsrc