15. WMLScript
WMLBrowser Standard Library
WMLScript's
WMLBrowser standard library contains seven functions in total. They
are used to control the WML browser or to get information from it.
15.1. Going Forwards /
Backwards to WML Cards: go() and prev() Functions
The
go() function and the prev() function of the WMLBrowser standard library are
used to go forwards and backwards to WML cards respectively.
The syntax of go() is as follows:
WMLBrowser.go(url);
url
is the URL of the WML card to go to. For example:
WMLBrowser.go("wmlscript_tutorial.wml");
The
prev() function does
not take any parameters. Its syntax is like this:
WMLBrowser.prev();
Both
go() and prev()
return an empty string if everything works fine. They return
an invalid value if errors occur.
Note
that the WML browser will load the target card only when it takes
back control from the WMLScript interpreter.
Suppose
a script calls go() or prev() multiple times before the
WML browser takes back control. When the WML browser resumes control,
it will only load the card specified by the last call. For example,
let's say you call the following script from a WML card:
extern
function
example_func1() { WMLBrowser.go("wml_tutorial.wml"); WMLBrowser.go("wmlscript_tutorial.wml"); }
When
the WML browser receives control, it will load the WML document
wmlscript_tutorial.wml
specified in the last statement.
Here
is another example:
extern
function
example_func2() { WMLBrowser.go("wml_tutorial.wml"); WMLBrowser.go("wmlscript_tutorial.wml"); WMLBrowser.prev(); }
When
the WML browser receives control, it will go to the previous card.
If
the script to be called is like this:
extern
function
example_func3() { WMLBrowser.prev(); WMLBrowser.prev(); }
The
WML browser will go backward once, but not twice, when it takes back
control from the WMLScript interpreter.
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