chirs wrote on 28 Nov 2003:
Thank you a lot. The only thing is if the user typed something
in box2 and then press ctrl-v, it clears the box2. But this can
be fixed. My question is why you use
document.forms['myForm'].elements['myText'].value instead of
document.myForm.myText.value? I also read some book saying I
do not need to put type="text/javascript" in <SCRIPT> since it
is default.
Then that book is, quite frankly, a load of crap and I suggest you
get a new one. It states quite clearly in the HTML 4.01 specification
(the latest) that there is no such thing as a default scripting
language, and that the type attribute is required. This applies to
XHTML, and possibly XML (but I have no knowledge of the latter, so
you'd have to check that). Also, the language attribute in SCRIPT
elements has been deprecated under the Strict document type. If I
were you, I'd quote the following (up to, and including, the HTTP
header description) to the publisher and author of that book*:
18.2.1 The SCRIPT element
<!ELEMENT SCRIPT - - %Script; -- script statements -->
<!ATTLIST SCRIPT
charset %Charset; #IMPLIED -- char encoding of linked resource --
type %ContentType; #REQUIRED -- content type of script language --
src %URI; #IMPLIED -- URI for an external script --
defer (defer) #IMPLIED -- UA may defer execution of script --
Attribute definitions
type = content-type [p.53] [CI] [p.49]
This attribute specifies the scripting language of the element’s
contents and overrides the default scripting language. The
scripting language is specified as a content type (e.g.,
"text/javascript"). Authors must supply a value for this attribute.
There is no default value for this attribute.
language = cdata [p.50] [CI] [p.49]
Deprecated. [p.38] This attribute specifies the scripting language
of the contents of this element. Its value is an identifier for the
language, but since these identifiers are not standard, this
attribute has been deprecated [p.38] in favor of type.
The above is abridged: the full description is under section 18,
Scripts, of the HTML 4.01 Specification (24 Dec 1999).
The 'default scripting language' referred to in the description of
the type attribute refers to the use of HTTP headers or META elements
(examples below) to identify the default language. If you use
intrinsic events (onclick, onload, etc), you /must/ use one of those
methods to declare the language. The only reason why browsers execute
scripts lacking such declarations is because of the expectation that
authors will not add them, so they use their own defaults. You should
not rely on that behaviour - browsers are not required to do it, and
could remove such support at any time and still conform to the HTML
specification.
To declare the default language use one of these (the latter can only
be done server-side, such as through the use of PHP or similar):
In the document HEAD:
<META http-equiv="Content-Script-Type" content="text/javascript">
As a HTTP header:
Content-Script-Type: text/javascript
As for your second question (why use the forms and elements
collections). I was recently made aware by others in this group that
not all browsers interpret the line below correctly.
document.myForm.myText.value = "";
To the likes of Mr Nielsen and Mr Lahn: My description is from
memory, so I might be a little (or a lot) off. Please correct me if
I'm wrong.
This is because myForm is not actually a property of the document
object, and myText is not a property of the Form object. In that
line, they are being accessed like globals, and not all browsers
support this. However, the document object uses a collection (forms)
to refer to every form that appears in the document. Likewise, the
Form object uses a collection (elements) to refer to every form
element in the form. These collections are defined in both Netscape's
(earlier) JavaScript language specification, and the DOM
specification, and should therefore be supported by any browser that
implements JavaScript or the DOM. Basically, using the statement
below instead of the one above, means that your script will be
executed properly on more browsers than it otherwise would, and so
your possible user base will be larger.
document.forms['myForm'].elements['myText'].value = "";
The last point about this syntax, is that you can use special
characters. If you had the name, home-phone, you couldn't use the
syntax you originally used. The hyphen would be interpreted as the
subtraction operator, and the script would break. However, it's
perfectly legal to do:
document.forms['someForm'].elements['home-phone']....
Sorry if I came off aggressively earlier - it wasn't directed at you.
I'm firmly in the "follow the standards" camp with HTML, and I'm
quite disgusted that a book would /recommend/ breaking the HTML
standard.
I hope that I've answered your questions.
Mike
* I would check first that the use of META or HTTP headers to declare
the default language isn't mentioned earlier in the book.
