call javascript function for every nth user

Question

I am collecting some sample data on my site and for now just want to collect data from say 10% of my visitors using a javascript function.

One way I can think of is to pick a number between 1 to 10 randomly and if its 10 then call the JS function to collect data else do nothing.

Also the data set need not be exactly from the 10% of users but a approximate number would also do for me.

I am Looking for suggestions on an alternate or better way to accomplish this.

Answer 1

You could keep a server side counter (in a DB for example) that checks before it delivers the page - if the counter is divisible by 10 then it includes the Javascript in the template, otherwise, the Javascript is omitted.

Of course, this is a very generic answer - how easy this would be to implement completely depends on your knowledge of server side scripting and the framework of your site.

Answer 2

I would do something like so. Meets the requirement for not exactly 10% as well. If you needed more exact results however this would definitely be something better done on the server side.

Live Demo

if(Math.random() * 100 >90){
   // greater than 90, so theoretically should only happen 1 out of 10 times do your stuff.  
}else{
    // Do nothing
}