Java Reference
In-Depth Information
platform used in combination with WML to provide client-side procedural logic. Like WML,
WMLScript is compiled through a WAP gateway into binary form to provide intelligence to
mobile clients. This section will be used to present the WMLScript language and its libraries; it
concludes with an example illustrating the use of WMLScript to perform client-side validation.
Calling WMLScript from WML
For a WMLScript function to be called from WML, the function must be declared within its
source file using the
extern
keyword. The syntax for calling a function is as follows:
sourcefile.wmls#functionname(arguments)
WML calls the WMLScript function through a hyperlink such as the
<a></a>
anchor tag or the
<go></go>
action tag. For example, a fictional WMLScript function call could be triggered
from an anchor tag such as:
<a href=”sourcefile.wmls#functionname(arguments)”>Click Here!</a>
Language Basics
WMLScript uses virtually the same syntax as JavaScript. Some of the basic language rules
include
•
All statements must end with a semicolon (;)
•
Variables are declared using the
var
keyword (for example,
var counter=0;
)
•
Multiline comments are surrounded by
/* */
; single-line comments begin with
//
•
The language is case sensitive
•
All WMLScript code must live inside a function
•
The language is comprised of six standard libraries:
Lang
,
Float
,
String
,
URL
,
WMLBrowser
, and
Dialogs
•
No run-time or compile-time type checking is done
•
The language supports five internal data types:
Boolean
,
Integer
,
Floating-point
,
String
, and
Invalid
WMLScript functions feature the following syntax:
function new_function(parameters)
{
code body
}
To return a value from a function, use the
return
keyword.
