What can you do after the HTML data arrives in the client browser? Well, with JavaScript almost anything ;-)) Here is the java code for a simple 'hello world' script -
<script type="text/javascript" language="javascript">
document.write ('Hello World'); // welcome to the Java World! ;-))
</script>
It seems some older browsers will not understand the line document.write(...), and coders provide protection by tell the browser it is all an HTML comment, thus can be skipped, by adding -
<script type="text/javascript" language="javascript">
<!-- Begin
document.write ('Hello World');
// end -->
</script>
For a start javascript, like other client side scripts, like MS VB Script, allows coders to quickly see and change HTML effects. For example, how can you see each of the table borders, 0 to 6, one after the other, just be able to see and judge the different effects? Well with java, see here. There is literally miles of sample javascript out there, and part of knowing Java is to have browsed through, and where needed copied, tried, modified, some sample javascript, or written own ... Try below, first -
Free JavaScripts provided
by The JavaScript Source
I have some samples on the site, sometimes where I have taken the code, from say the above, and
modified it, to hopefully add to the rich work that had already been done. One in pure simple
form, it already being delightful in its display. Try these -
* a mouse chasing, analogue clock, with circling day, date information, seeing is believing, an
anoclk.htm. Or
* paint phases of the moon, a Java Moon 1, or Java
Moon 2, or Moon Phases, or
* a sample library type Java Include or
* Multiple Images on mouse over, a Java Menu, or
* Set of five (5) Java (flying) Planes! or Clock and Planes combined!
* Javascript stopwatch.
* A simple page visit counter, using cookies.
... java.net is the realization of a vision of a diverse group of engineers, researchers, technologists, and evangelists at Sun Microsystems, Inc. to provide a common area for interesting conversations and innovative development projects related to Java (™) technology. ...
Looking for some references -
http://wp.netscape.com/eng/mozilla/3.0/handbook/javascript/
http://www.webreference.com/js/
<appears broken!>http://doc.h9d.com/javascript/refp_01.htm
http://www.htmlhelp.org/reference/html40/forms/select.html
...
Of course, to work well with javascript, you must also know HTML, DHTML, and Intrinsic HTML Controls. Each browser, like Internet Explorer, supports a set of controls that are built into the browser itself. These controls, called intrinsic HTML controls, do not have to be downloaded across the Internet to be used on the client machine. Intrinsic controls are not defined with the <OBJECT> </OBJECT> tags, as ActiveX controls are. Instead, they are defined either with the <INPUT> tag or such special tags as the <SELECT></SELECT> tags or <TEXTAREA></TEXTAREA> tags. The intrinsic controls are used with these tags because these tags support the original HTML specification for controls on a web page. Prior to the introduction of ActiveX controls and downloadable objects, HTML supported several controls through these special HTML tags. For example, inserting a button into a web page is done with the <INPUT> tag, as shown here:
<INPUT TYPE="BUTTON" NAME="Command1">
The intrinsic controls are often used in conjunction with an HTML form. Forms are created with the
<FORM></FORM> tags. Controls are subsequently defined inside the form. The following
code defines two text fields and a button inside a form:
<FORM NAME="frmOne">
<INPUT TYPE="TEXT" NAME="Text1">
<INPUT TYPE="TEXT" NAME="Text2"><BR>
<INPUT TYPE="BUTTON" NAME="Command1">
</FORM>
When controls are defined inside a form, the Internet Explorer automatically supports their events
in VBScript code. In the above case, the button supports an OnClick event that the Internet
Explorer will fire, executing code in a VBScript event-handling subroutine, shown here, but this
could just as well be a javascript: handler ...
<SCRIPT type="text/VBScript" LANGUAGE="VBScript">
Sub Command1_OnClick
MsgBox "Event Routine Fired!"
End Sub
</SCRIPT>
Lots of information is documented on the W3C sites, Here is the W3C FORM reference - http://www.w3.org/TR/html4/interact/forms.html#h-17.3 - where you can read -
<!ELEMENT FORM - - (%block;|SCRIPT)+ -(FORM) -- interactive form --> <!ATTLIST FORM %attrs; -- %coreattrs, %i18n, %events -- action %URI; #REQUIRED -- server-side form handler -- method (GET|POST) GET -- HTTP method used to submit the form-- enctype %ContentType; "application/x-www-form-urlencoded" accept %ContentTypes; #IMPLIED -- list of MIME types for file upload -- name CDATA #IMPLIED -- name of form for scripting -- onsubmit %Script; #IMPLIED -- the form was submitted -- onreset %Script; #IMPLIED -- the form was reset -- accept-charset %Charsets; #IMPLIED -- list of supported charsets -- >
Start tag: required, End tag: required
Attributes defined elsewhere
The FORM element acts as a container for controls.
... and on to next ...
<!ENTITY % InputType "(TEXT | PASSWORD | CHECKBOX | RADIO | SUBMIT | RESET | FILE | HIDDEN | IMAGE | BUTTON)" > <!-- attribute name required for all but submit and reset --> <!ELEMENT INPUT - O EMPTY -- form control --> <!ATTLIST INPUT %attrs; -- %coreattrs, %i18n, %events -- type %InputType; TEXT -- what kind of widget is needed -- name CDATA #IMPLIED -- submit as part of form -- value CDATA #IMPLIED -- Specify for radio buttons and checkboxes -- checked (checked) #IMPLIED -- for radio buttons and check boxes -- disabled (disabled) #IMPLIED -- unavailable in this context -- readonly (readonly) #IMPLIED -- for text and passwd -- size CDATA #IMPLIED -- specific to each type of field -- maxlength NUMBER #IMPLIED -- max chars for text fields -- src %URI; #IMPLIED -- for fields with images -- alt CDATA #IMPLIED -- short description -- usemap %URI; #IMPLIED -- use client-side image map -- ismap (ismap) #IMPLIED -- use server-side image map -- tabindex NUMBER #IMPLIED -- position in tabbing order -- accesskey %Character; #IMPLIED -- accessibility key character -- onfocus %Script; #IMPLIED -- the element got the focus -- onblur %Script; #IMPLIED -- the element lost the focus -- onselect %Script; #IMPLIED -- some text was selected -- onchange %Script; #IMPLIED -- the element value was changed -- accept %ContentTypes; #IMPLIED -- list of MIME types for file upload -- >
Start tag: required, End tag: forbidden
Attribute definitions
Attributes defined elsewhere
The control type defined by the INPUT element depends on the value of the type attribute:
Note. Application designers should note that this mechanism affords only light security protection. Although the password is masked by user agents from casual observers, it is transmitted to the server in clear text, and may be read by anyone with low-level access to the network.
When a pointing device is used to click on the image, the form is submitted and the click coordinates passed to the server. The x value is measured in pixels from the left of the image, and the y value in pixels from the top of the image. The submitted data includes name.x=x-value and name.y=y-value where "name" is the value of the name attribute, and x-value and y-value are the x and y coordinate values, respectively.
If the server takes different actions depending on the location clicked, users of non-graphical browsers will be disadvantaged. For this reason, authors should consider alternate approaches:
... and on .. and on .. and on ...
JavaScript: The Definitive Guide
By David Flannagan; ISBN: 1-56592-235-2, 637 pages.
Second Edition, January 1997
<sample>
Synopsis
document.anchors.length
document.anchors[i]
HTML Syntax
An Anchor object is created by any standard HTML <A> tag that contains a <NAME>
attribute:
<A
NAME="anchor_name" links may refer to this anchor by this name
[ HREF=URL ] an anchor may also be a link
[ TARGET="window_name" ] links may refer to other windows
>
link text
</A>
</sample>
<quote>
The Web Design Group was founded to promote the creation
of non-browser specific, non-resolution specific, creative and
informative sites that are accessible to all users worldwide. To this
end, the WDG offers material on a wide range of HTML related topics. We hope that with this
site as a reference, you will be able to create Web sites that can be used by every person on
the Internet, regardless of browser, platform, or settings.
</quote>
<samples>
SELECT - Option Selector
Syntax | <SELECT>...</SELECT> |
---|---|
Attribute Specifications |
|
Contents | One or more OPTGROUP or OPTION elements |
Contained in | Block-level elements, inline elements except BUTTON |
The SELECT element defines a form control for the selection of options. While SELECT is most useful within a FORM, HTML 4.0 allows SELECT in any block-level or inline element other than BUTTON. However, Netscape Navigator will not display any SELECT elements outside of a FORM.
</sample>
The references are, of course a mixture of HTML code, so you can know where javascript can alter the contents of a page ... ;=))
AJR INW = http://www.irt.org/script/window.htm