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In order to turn it into the first (callable) part of an asynchronous UDF, you remove the return value (since the result is going to be returned asynchronously later on), and you add a trailing int parameter (we will explain its purpose in a bit):
this tutorial will be about using the Mootools JS library with ajax, if you dont know a thing about ajax you will do just fine with mootools. but you need to have know some javascript to keep up.
Sun, Dec 20 | from Tutorialized.com