Calling a Function from a WML Card

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URLs are used to call WMLScript functions from a WML card. The URL specifies the location of the WMLScript file and the name of the function to be called. It should be in the form:


http://domain_name/path/wmlscript_filename#function_name(argument1, argument2, ...)


The URL can be in absolute or relative form.

The following example demonstrates how to use anchor links to call WMLScript functions from a WML card. Suppose we have a WMLScript file called wmlscript.wmls, which contains the following script:


extern function wmlscript_function()
{
  WMLBrowser.setVar("message", "Welcome to our WMLScript tutorial");
}


To call wmlscript_function() from a WML card, create an anchor link using the following WML markup. The script will be executed if you click the anchor link.


<a href="wmlscript.wmls#wmlscript_function()">Execute Script</a>


Or


<anchor>
  <go href="wmlscript.wmls#wmlscript_function()"/>
  Execute Script
</anchor>


Another way to call wmlscript_function() in a WML card is to place the URL in a WML event handler. The script will be executed when the WML event occurs. For example, the following markup instructs the WAP browser to call wmlscript_function() when the ontimer event is triggered:


<onevent type="ontimer">
  <go href="wmlscript.wmls#wmlscript_function()"/>
</onevent>
<timer value="50"/>


Four event types are supported in WML. They are ontimer, onenterbackward, onenterforward and onpick. Details about them can be found in the "WML Events and the <onevent> Tag" section of our WML tutorial.


Passing Arguments to Functions

The wmlscript_function() function above does not take any arguments. Now let's see how to pass arguments to functions. Suppose there is another function called addition() that takes two numbers as its arguments:


extern function addition(number1, number2)
{
  WMLBrowser.setVar("message", number1 + number2);
}


To call addition() from a WML card, we need to include two arguments in the URL. For example, to pass two integers 10 and 11 to addition(), we can make use of the following WML markup:


<a href="wmlscript.wmls#addition(10, 11)">Execute Script</a>


In some situations, what you want to pass into a WMLScript function is not a fixed value but is a WML variable. The following WML markup demonstrates how to pass two WML variables, wmlVar1 and wmlVar2, to the addition() function:


<card id="card1" title="WMLScript Tutorial">
  <onevent type="onenterforward">
    <refresh>
      <setvar name="wmlVar1" value="10"/>
      <setvar name="wmlVar2" value="11"/>
    </refresh>
  </onevent>

  <p>
    <a href="wmlscript.wmls#addition($(wmlVar1), $(wmlVar2))">Execute Script</a>
  </p>

  ...
</card>


When the WAP browser comes across the terms $(wmlVar1) and $(wmlVar2), it will substitute them with their stored value. So, the WML markup:


<a href="wmlscript.wmls#addition($(wmlVar1), $(wmlVar2))">Execute Script</a>


will become:


<a href="wmlscript.wmls#addition(10, 11)">Execute Script</a>


Note that if the value of wmlVar1 and wmlVar2 contains non-numeric characters, $(wmlVar1) and $(wmlVar2) have to be enclosed in quotes so that the values are passed into the function as string literals, like this:


<a href="wmlscript.wmls#addition('$(wmlVar1)', '$(wmlVar2)')">Execute Script</a>


Suppose the values of wmlVar1 and wmlVar2 are still 10 and 11 respectively. After substitution, the above WML markup will become:


<a href="wmlscript.wmls#addition('10', '11')">Execute Script</a>


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