Instead of using simple links, you can also set JavaScript links using FusionMaps i.e., you can invoke a JavaScript function present in the same page (in which the map is present) when the end viewer clicks a map element. To attain this, all you need to do is place the name of JavaScript function instead of the link URL, as under:

<entity id='NA' value='515' link="JavaScript:myJS('NA, 515');"/>

In the above code, myJS refers to a custom JavaScript function present in the HTML page that embeds this map. You can also specify any number of parameters for this function. However, you cannot use a semi-colon within the declaration.

Since FusionCharts v3.1, we have also introduced the following new syntax:

<set label='USA' value='235' link="j-myJS-NA,515"/>

The classical function-call notation of JavaScript has been replaced by following expression

j-{user function name}-{parameter}

The {user function name} is a user-defined function. It will receive the parameters as a single de-limiter separated string.
The {parameters} is a de-limiter separated value field. The parameter field should not be enclosed within quotes. Using this method, you can just pass one parameter from chart to your JavaScript. So, when you need to pass multiple parameters, combine them using a delimiter in XML, and then in your JavaScript method split it again.

The classical notation will be evaluated faster since no String decomposition takes place. However, the new syntax removes all the problems with nested quotation marks.

When you now click the map element, myJS function would be invoked and 'NA, 515' would be passed to the function as the function parameter. Here, we've passed the entity label and value just for demonstration purposes. In actual apps, you can pass identifier numbers or strings to each data. When the user clicks on the link, these identifiers can be sent back to your JavaScript functions for further actions (like loading detailed data for that identifier using AJAX or anything - the possibilities are endless).

Let's quickly put up an example for this kind of links. We'll create a simple World Population Map. Each continent when clicked, would pass its label and value to our custom JavaScript function myJS, which (for the sake of demonstration) would just write it out in an alert box.

We create JSExample.html for this example in DrillDown folder. It contains the following HTML code:

Here, we've a defined a function myJS which will respond to the clicks generated from the map.

And now JSExample.xml looks as under:

When you view the map and click on a continent, you'll see something like under: