JavaScript Bible, Gold Edition part 43 pptx

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Part III ✦ Document Objects Reference
that you can control for a newly created window in all browsers. Except where
noted, all Boolean values default to
yes if you do not specify the third parameter.
Table 16-3 window.open() Method Attributes
Controllable via Script
Attribute Browsers Description
alwaysLowered
3
NN4+ (Boolean) Always behind other browser windows
alwaysRaised
3
NN4+ (Boolean) Always in front of other browser windows
channelmode IE4+ (Boolean) Theater mode with channel band
(default is no)
copyhistory NN2+, IE3+ (Boolean) Duplicates Go menu history for new
window
dependent NN4+ (Boolean) Subwindow closes if the opener
window closes
directories NN2+, IE3+ (Boolean) “What’s New” and other buttons
in the row
fullscreen IE4+ (Boolean) No title bar or menus (default is no)
height NN2+, IE3+ (Integer) Content region height in pixels
hotkeys NN4+ (Boolean) If true, disables menu shortcuts
(except Quit and Security Info) when menubar is
turned off
innerHeight
4
NN4+ (Integer) Content region height; same as old
height property

innerWidth
4
NN4+ (Integer) Content region width; same as old
width property
left IE4+ (Integer) Horizontal position of top-left corner on
screen
location NN2+, IE3+ (Boolean) Field displaying the current URL
menubar
1
NN2+, IE3+ (Boolean) Menubar at top of window
outerHeight
4
NN4+ (Integer) Visible window height
outerWidth
4
NN4+ (Integer) Visible window width
resizable
2
NN2+, IE3+ (Boolean) Interface elements that allow resizing
by dragging
screenX
4
NN4+ (Integer) Horizontal position of top-left corner on
screen
screenY
4
NN4+ (Integer) Vertical position of top-left corner on
screen
scrollbars NN2+, IE3+ (Boolean) Displays scrollbars if document is larger
than window

windowObject.open()
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Attribute Browsers Description
status NN2+, IE3+ (Boolean) Statusbar at bottom of window
titlebar
3
NN4+ (Boolean) Title bar and all other border elements
title IE5 (Boolean) Title bar
toolbar NN2+, IE3+ (Boolean) “Back,” “Forward,” and other buttons in
the row
top IE4+ (Integer) Horizontal position of top-left corner on
screen
width NN2+, IE3+ (Integer) Content region width in pixels
z-lock
3
NN4+ (Boolean) Window layer is fixed below browser
windows
1 Not on Macintosh because the menubar is not in the browser window; when off in NN4/Mac,
displays an abbreviated Mac menubar.
2 Macintosh windows are always resizable.
3 Requires a signed script.
4 Requires a signed script to size or position a window beyond safe threshold.
Boolean values are handled a bit differently than you might expect. The value for
true can be either yes, 1, or just the feature name by itself; for false, use a value
of
no or 0. If you omit any Boolean attributes, they are rendered as false.
Therefore, if you want to create a new window that shows only the toolbar and
statusbar and is resizable, the method looks like this:
window.open(“newURL”,”NewWindow”, “toolbar,status,resizable”)

A new window that does not specify the height and width is set to the default
size of the browser window that the browser creates from a File menu’s New Web
Browser command. In other words, a new window does not automatically inherit
the size of the window making the
window.open() method call. A new window
created via a script is positioned somewhat arbitrarily, unless you use the window
positioning attributes available in NN4+ and IE4+. Notice that the position attributes
are different for each browser (
screenX and screenY for NN; left and top for IE).
You can include both sets of attributes in a single parameter string because the
browser ignores attributes it doesn’t recognize.
Netscape-only signed scripts
Many NN-specific attributes are deemed to be security risks and thus require
signed scripts and the user’s permission before they are recognized. If the user fails
to grant permission, the secure parameter is ignored.
A couple of these attributes have different behaviors on different operating
system platforms, due to the way the systems manage their application windows.
For example, the
alwaysLowered, alwaysRaised, and z-locked styles can exist in
layers that range behind Navigator’s own windows in the Windows platform; on the
Mac, however, such windows are confined to the levels occupied by Navigator. The
difference is that Windows allows windows from multiple applications to interleave
each other, while the Mac keeps each application’s windows in contiguous layers.
windowObject.open()
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To apply signed scripts to opening a new window with the secure window fea-
tures, you must enable
UniversalBrowserWrite privileges as you do for other
signed scripts (see Chapter 46). A code fragment that generates an

alwaysRaised
style window follows:
<SCRIPT LANGUAGE=”JavaScript” ARCHIVE=”myJar.jar” ID=”1”>
function newRaisedWindow() {
netscape.security.PrivilegeManager.enablePrivilege(“UniversalBrowserWrite”)
var newWindow = window.open(“”,””,”HEIGHT=100,WIDTH=300,alwaysRaised”)
netscape.security.PrivilegeManager.disablePrivilege(“UniversalBrowserWrite”)
var newContent = “<HTML><BODY><B> “On top of spaghetti!”</B>”
newContent += “<FORM><CENTER><INPUT TYPE=’button’ VALUE=’OK’”
newContent += “onClick=’self.close()’></CENTER></FORM></BODY></HTML>”
newWindow.document.write(newContent)
newWindow.document.close()
}
</SCRIPT>
You can experiment with the look and behavior of new windows with any combi-
nation of attributes with the help of the script in Listing 16-25. This page presents a
table of all NN-specific new window Boolean attributes and creates a new 300×300
pixel window based on your choices. This page assumes that if you are using NN4,
you have codebase principals turned on for signed scripts (see Chapter 46).
Be careful with turning off the title bar and hotkeys. With the title bar off, the
content appears to float in space, because absolutely no borders are displayed.
With hotkeys still turned on, you can use Ctrl+W to close this borderless window
(except on the Mac, for which the hotkeys are always disabled with the title bar off).
This is how you can turn a computer into a kiosk by sizing a window to the screen’s
dimensions and setting the window options to
“titlebar=no,hotkeys=no,
alwaysRaised=yes”
.
Listing 16-25: New Window Laboratory
<HTML>

<HEAD>
<TITLE>window.open() Options</TITLE>
<SCRIPT LANGUAGE=”JavaScript”>
var isNav4 = (navigator.appName == “Netscape” &&
navigator.appVersion.charAt(0) >= 4) ? true : false
function makeNewWind(form) {
if (isNav4) {
netscape.security.PrivilegeManager.enablePrivilege(“UniversalBrowserWrite”)
}
var attr = “HEIGHT=300,WIDTH=300”
for (var i = 0; i < form.elements.length; i++) {
if (form.elements[i].type == “checkbox”) {
attr += “,” + form.elements[i].name + “=”
attr += (form.elements[i].checked) ? “yes” : “no”
}
}
var newWind = window.open(“bofright.htm”,”subwindow”,attr)
if (isNav4) {
windowObject.open()
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Chapter 16 ✦ Window and Frame Objects
netscape.security.PrivilegeManager.revertPrivilege(“UniversalBrowserWrite”)
}
}
</SCRIPT>
</HEAD>
<BODY>
<FORM>
<B>Select new window options:</B>
<TABLE BORDER=2>

<TR>
<TD COLSPAN=2 BGCOLOR=”yellow” ALIGN=”middle”>All Browsers Features:</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”toolbar”>toolbar</TD>
<TD><INPUT TYPE=”checkbox” NAME=”location”>location</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”directories”>directories</TD>
<TD><INPUT TYPE=”checkbox” NAME=”status”>status</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”menubar”>menubar</TD>
<TD><INPUT TYPE=”checkbox” NAME=”scrollbars”>scrollbars</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”resizable”>resizable</TD>
<TD><INPUT TYPE=”checkbox” NAME=”copyhistory”>copyhistory</TD>
</TR>
<TR>
<TD COLSPAN=2 BGCOLOR=”yellow” ALIGN=”middle”>Communicator Features:</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”alwaysLowered”>alwaysLowered</TD>
<TD><INPUT TYPE=”checkbox” NAME=”alwaysRaised”>alwaysRaised</TD>
</TR>
<TR>
<TD><INPUT TYPE=”checkbox” NAME=”dependent”>dependent</TD>
<TD><INPUT TYPE=”checkbox” NAME=”hotkeys” CHECKED>hotkeys</TD>
</TR>

<TR>
<TD><INPUT TYPE=”checkbox” NAME=”titlebar” CHECKED>titlebar</TD>
<TD><INPUT TYPE=”checkbox” NAME=”z-lock”>z-lock</TD>
</TR>
<TR>
<TD COLSPAN=2 ALIGN=”middle”><INPUT TYPE=”button” NAME=”forAll”
VALUE=”Make New Window” onClick=”makeNewWind(this.form)”></TD>
</TR>
</TABLE>
<BR>
</FORM>
</BODY>
</HTML>
windowObject.open()
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Specifying a window name
Getting back to the other parameters of window.open(), the second parameter is
the name for the new window. Don’t confuse this parameter with the document’s title,
which would normally be set by whatever HTML text determines the content of the
window. A window name must be the same style of one-word identifier that you use
for other object names and variables. This name is also an entirely different entity
than the
window object that the open() method returns. You don’t use the name in
your scripts. At most, the name can be used for
TARGET attributes of links and forms.
Loading content into a new window
A script generally populates a window with one of two kinds of information:
✦ An existing HTML document whose URL is known beforehand
✦ An HTML page created on the fly

To create a new window that displays an existing HTML document, supply the
URL as the first parameter of the
window.open() method. If your page is having dif-
ficulty loading a URL into a new page (except as noted in the sidebar “A Navigator 2
Bug Workaround”), try specifying the complete URL of the target document
(instead of just the filename).
Leaving the first parameter as an empty string forces the window to open with a
blank document, ready to have HTML written to it by your script (or loaded sepa-
rately by another statement that sets that window’s location to a specific URL). If
you plan to write the content of the window on the fly, assemble your HTML con-
tent as one long string value and then use the
document.write() method to post
that content to the new window. If you plan to append no further writing to the
page, also include a
document.close() method at the end to tell the browser that
you’re finished with the layout (so that the
Layout:Complete or Done message
appears in the statusbar, if your new window has one).
A call to the
window.open() method returns a reference to the new window’s
object if the window opens successfully. This value is vitally important if your
script needs to address elements of that new window (such as when writing to its
document).
To allow other functions in your script to reference the subwindow, you should
assign the result of a
window.open() method to a global variable. Before writing to
the new window the first time, test the variable to make sure that it is not a
null
value — the window may have failed to open because of low memory, for instance.
If everything is okay, you can use that variable as the beginning of a reference to

any property or object within the new window. For example:
var newWindow

function createNewWindow() {
newWindow = window.open(“”,””)
if (newWindow != null) {
newWindow.document.write(“<HTML><HEAD><TITLE>Hi!</TITLE></HEAD>”)
}
}
That global variable reference continues to be available for another function that
perhaps closes the subwindow (via the
close() method).
windowObject.open()
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Chapter 16 ✦ Window and Frame Objects
When scripts in the subwindow need to communicate with objects and scripts in
the originating window, you must make sure that the subwindow has an
opener
property if the level of JavaScript in the visitor’s browser doesn’t automatically
supply one. See the discussion about the
window.opener property earlier in this
chapter.
Invoking multiple
window.open() methods with the same window name parameter
(the second parameter) does not create additional copies of that window in Netscape
browsers (although it does in Internet Explorer). JavaScript prevents you from creat-
ing two windows with the same name. Also be aware that a
window.open() method
does not bring an existing window of that name to the front of the window layers: Use
window.focus() for that.

windowObject.open()
A Navigator 2 Bug Workaround
If you’re concerned about backward compatibility with Navigator 2, you should be aware of
a bug in the Macintosh and UNIX flavors of the browser. In those versions, if you include a
URL as a parameter to
window.open(), Navigator opens the window but does not load the
URL. A second call to the
window.open() method is required. Moreover, the second
parameter must be an empty string if you add any third-parameter settings. Here is a sam-
ple listing you can adapt for your own usage:
<HTML>
<HEAD>
<TITLE>New Window</TITLE>
<SCRIPT LANGUAGE=”JavaScript”>
// workaround for window.open() bug on X and Mac platforms
function makeNewWindow() {
var newWindow =
window.open(“”,””,”status,height=200,width=300”)
if (parseInt(navigator.appVersion) == 2 && navigator.appName ==
“Netscape”) {
newWindow =
window.open(“”,””,”status,height=200,width=300”)
}
}
</SCRIPT>
</HEAD>
<BODY>
<FORM>
<INPUT TYPE=”button” NAME=”newOne” VALUE=”Create New Window”
onClick=”makeNewWindow()”>

</FORM>
</BODY>
</HTML>
This workaround can also be used without penalty in Windows versions of Navigator.
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Part III ✦ Document Objects Reference
Internet Explorer idiosyncracies
Creating subwindows in IE can be complicated at times by undesirable behavior
by the browser. One of the most common problems occurs when you attempt to
use
document.write() to put content into a newly created window. IE, including
some of the latest versions, fails to complete the window opening job before the
script statement that uses
document.write() executes. This causes a script error
because the reference to the subwindow is not yet valid. To work around this, you
should put the HTML assembly and
document.write() statements in a separate
function that gets invoked via a
setTimeout() method after the window is created.
You can see an example of this in Listing 16-26.
Another problem that affects IE is the occasional security violation (“access
denied”) warning when a script attempts to access a subwindow. This problem goes
away when the page that includes the script for opening and accessing the subwin-
dow is served from an http server, rather than accessed from a local hard disk.
Finally, an all-too common bug in Windows 95/98 allows the Registry to become
mildly corrupted in some key areas that IE needs for opening and referencing new
windows. The most common symptom of the problem is a script error on the state-
ment that invokes
window.open(), but other indications include error messages
that the

document.write() method is not supported in the subwindow or that the
“RPC server” is not available. The problem cannot be fixed by JavaScript but
requires human intervention on the affected PC. Here are the steps to repair the
problem:
1. Click Start and then click Run.
2. In the Open box, type the following line: regsvr32 actxprxy.dll
3. Click OK and then click OK again after you receive the following message:
DllRegisterServer in actxprxy.dll succeeded.
4. Click Start and then click Run.
5. In the Open box, type the following line:
regsvr32 shdocvw.dll
6. Click OK and then click OK again after you receive the following message:
DllRegisterServer in shdocvw.dll succeeded.
7. Shut down and restart your computer.
The corruption is reported to be caused by application installers and unin-
stallers that don’t clean up after themselves the way they should. The fact that this
problem is rather common in IE4 under both Windows 95 and 98 might make you
gun-shy about utilizing multiple windows in your application.
Example (with Listing 16-26) on the CD-ROM
Related Items: window.close(), window.blur(), window.focus() methods;
window.closed property.
On the
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windowObject.open()
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Chapter 16 ✦ Window and Frame Objects
print()
Returns: Nothing.
NN2 NN3 NN4 NN6 IE3/J1 IE3/J2 IE4 IE5 IE5.5
Compatibility ✓✓ ✓✓

The print() method provides a scripted way of sending the window or a frame
from a frameset to the printer. In all cases, the Print dialog box appears for the user
to make the typical printer choices when printing manually. This prevents a rogue
print() command from tying up a printer without the user’s permission.
The precise behavior of the
print() method varies a bit with the different ways
NN and IE (not to mention operating systems) handle printing. In NN4+ (except for
the Windows OS), you can print all frames of a frameset in one
print() command
when it is invoked for the framesetting (parent) document. NN4 for Windows, how-
ever, does not print the entire frameset at once. You can write a script that iterates
through all frames and prints them with delays to let the content be sent to the
print spooler:
function printFrames(n) {
parent.frames[n++].print()
if (n < parent.frames.length) {
setTimeout(“printFrames(“ + n + “)”,5000)
}
}
Invoke this function as printFrames(0), and the function does the rest.
In IE5, the print dialog box gives the user the choice of printing just one frame or
all of the frames. Make sure that the
print() method is invoked for the desired
frame when you want only that frame to print. The browser defaults to printing just
that frame.
IE5 introduces some print-specific event handlers that are triggered by scripted
printing as well as manual printing. The events begin to fire after the user has
accepted the Print dialog box. An
onBeforePrint event handler can be used to
show content that might be hidden from view but should appear in the printout.

After the content has been sent to the print spooler, the
onAfterPrint event can
restore the page.
Example (with Listings 16-27 and 16-28) on the CD-ROM
NN4 printing anomalies
The Windows and Unix versions of NN4 handle printing in a way that can cause
the page to not print what the user sees because before the page prints, it is loaded
into a hidden window. Any immediate scripts in the page run again, but any user-
induced, scripted content modifications will most likely not be a part of the page.
On the
CD-ROM
windowObject.print()
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Part III ✦ Document Objects Reference
While there is no known workaround for resurrecting modified content, your
script can at least know if the page is being loaded into one of these hidden win-
dows: The NN-specific
window.outerHeight and window.outerWidth properties
are zero. If you don’t want an immediate script statement to run before being
printed, use an
if construction to let the nested statement(s) run only if either of
those dimension properties is greater than zero.
Printing in IE4
While the window.print() method is not available in IE4, it is possible to script
printing in the Win32 OS platforms via the built-in browser object. To use this
ActiveX object, you must first include the following HTML somewhere in your
document (at the end of the BODY is fine):
<OBJECT ID=”IEControl” WIDTH=0 HEIGHT=0
CLASSID=”clsid:8856F961-340A-11D0-A96B-00C04FD705A2”>
</OBJECT>

The long CLASSID attribute must be copied exactly. This HTML adds an object to
the document object model that can be scripted. The object has several commands
available, one of which provides printing services. The commands are numbered,
and the one for printing is the following:
IEControl.ExecWB(6, 1)
If the user cancels the Print dialog box, a script error may appear, so be sure to
trap for errors (see the
window.onerror property earlier in this chapter). If you
change the second parameter to 2, the Print dialog box does not appear, but that
isn’t a very user-friendly way to treat printing.
Related Items:
window.back(), window.forward(), window.home(),
window.find() methods.
prompt(“message”, “defaultReply”)
Returns: String of text entered by user or null.
NN2 NN3 NN4 NN6 IE3/J1 IE3/J2 IE4 IE5 IE5.5
Compatibility ✓✓ ✓✓ ✓ ✓ ✓✓✓
The third kind of dialog box that JavaScript can display includes a message from
the script author, a field for user entry, and two buttons (OK and Cancel, or Yes and
No on Mac versions of Navigator 2 and 3). The script writer can supply a prewritten
answer so that a user confronted with a prompt dialog box can click OK (or press
Enter) to accept that answer without further typing. Supplying both parameters to
the
window.prompt() method is important. Even if you don’t want to supply a
default answer, enter an empty string as the second parameter:
prompt(“What is your postal code?”,””)
If you omit the second parameter, JavaScript inserts the string undefined into
the dialog box’s field. This string is disconcerting to most Web page visitors.
windowObject.prompt()
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Chapter 16 ✦ Window and Frame Objects
The value returned by this method is a string in the dialog box’s field when the
user clicks the OK button. If you’re asking the user to enter a number, remember
that the value returned by this method is a string. You may need to perform data-
type conversion with the
parseInt() or parseFloat() functions (see Chapter 42)
to use the returned values in math calculations.
When the user clicks the prompt dialog box’s OK button without entering any
text into a blank field, the returned value is an empty string (
“”). Clicking on the
Cancel button, however, makes the method return a
null value. Therefore, the
scripter must test for the type of returned value to make sure that the user entered
some data that can be processed later in the script, as in
var entry = prompt(“Enter a number between 1 and 10:”,””)
if (entry != null) {
//statements to execute with the value
}
This script excerpt assigns the results of the prompt dialog box to a variable and
executes the nested statements if the returned value of the dialog box is not null
(if the user clicked the OK button). The rest of the statements then include data
validation to make sure that the entry is a number within the desired range (see
Chapter 43).
It may be tempting to use the prompt dialog box as a handy user input device.
But, as with the other JavaScript dialog boxes, the modality of the prompt dialog
box is disruptive to the user’s flow through a document and can also trap auto-
mated macros that some users activate to capture Web sites. In forms, HTML fields
are better user interface elements for attracting user text entry. Perhaps the safest
way to use a prompt dialog box is to have it appear when a user clicks a button ele-
ment on a page — and then only if the information you require of the user can be

provided in a single prompt dialog box. Presenting a sequence of prompt dialog
boxes is downright annoying to users.
Example (with Figure 16-13 and Listing 16-29) on the CD-ROM
Related Items: window.alert(), window.confirm() method.
releaseEvents(eventTypeList)
Returns: Nothing.
NN2 NN3 NN4 NN6 IE3/J1 IE3/J2 IE4 IE5 IE5.5
Compatibility ✓
If your scripts have enabled NN4-specific event capture for the window object
(or
document or layer, for that matter), you can turn off that capture with the
releaseEvents() method. This method does not inhibit events from reaching
On the
CD-ROM
windowObject.releaseEvents()