Question

So how does JavaScript works in the new Flash Pro CS6?

To call JavaScript you are using the new interface:

/* js
alert("Hello from JavaScript");

*/

But how do you call to flash from JavaScript?

Answer 1

Check out this quick tutorial, it worked for me: http://circlecube.com/2010/12/actionscript-as3-javascript-call-flash-to-and-from-javascript/

That tutorial is fairly old (before CS6), so it explains how to call js from flash and vice versa. The essential part that you want is this actionScript:

ExternalInterface.addCallback("name_of_js_function", name_of_as3_function);

function name_of_as3_function():void {
    // I was called from javascript
}