TechNote (Archived)

Using asfunction

Flash 5's undocumented asfunction command allows an HREF link in an HTML-enabled text field, or a text field linked using the URL field in the Character panel, to call a user-defined function. Typically, URL text links in Flash are limited to calling other HTML pages, similar to the getURL action. Usingasfunction, a text link can call a function that can then perform a variety of ActionScript statements.

Syntax

The asfunction command can only be called from the URL field of the Character panel or from an HREF tag in an HTML-enabled text field.

 asfunction:functionName,parameter 

Note: One parameter can be passed to the function, delimited by a comma.

Arguments

functionName: Name of the user-defined function to be called when link is clicked.

parameter: Specifies the value to pass into the function.

Note: The function specified byfunctionName is called without concluding parentheses and must be defined in the Flash movie before being called.

Description

The asfunction command is used to call a function from a link in an HTML-enabled text field or from a text field linked using the URL field in the Character panel.

Examples

To see how asfunction works, add the following function definition to the first frame of a movie:

 function myFunction () {   trace("Testing asfunction..."); } 

Next, select a text block on the stage and open the Character panel (Window > Panels > Character). In the Character panel's URL field enter the following (as illustrated below):

 asfunction:myFunction 

Note: This is equivalent to assigning"<A HREF="asfunction:myFunction">Click here</A>" to an HTML-enabled text field variable.

Test the movie (Control > Test Movie) and click the linked text. The string "Testing asfunction..." should appear in the Output window. (If nothing appears in the Output window, double-check spelling and syntax in the URL field and the function definition.)

Passing a function parameter

You can pass a single, string parameter toasfunction. For example, modify the function declaration shown above as follows:

 function myFunction (param) {   trace("Testing asfunction with parameter: " + param); } 

Next, modify the asfunction call in the Character panel's URL field to include an argument:

 asfunction:myFunction,argument_1 

Note: This is equivalent to assigning"<A HREF="asfunction:myFunction,argument_1">Click here</A>" to an HTML-enabled text field variable.

The string "Testing asfunction with parameter: argument_1" should appear in the Output window when you test the movie in Flash.

Passing multiple function parameters

As mentioned above, the function called byasfunction is only passed a single string argument. One way to mimic passing multiple arguments is to separate the"arguments" using a predetermined string delimiter. Below, three comma-delimited arguments are passed tomyFunction.

 asfunction:myFunction,argument_1,argument_2,argument_3 

In the new version of myFunction, thesplit method is used to break the comma-delimited string into an array of arguments, argumentArray.

 function myFunction(param){   argumentArray = new Array;   argumentArray = param.split(",");   for (i=0; i< argumentArray.length; ++i){     trace("Function argument " + i + " = " + argumentArray[i]);   } } 

Testing the movie should result in the following being reported to the Output window:

 Function argument 0 =  argument_1
		

	 Function argument 1 =  argument_2
		

	 Function argument 2 =  argument_3 

Additional information

Using HTML formatting in Flash 5 (TechNote 14808) contains information on creating links in HTML-enabled text fields.

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