Fat finger control when a user double clicks several times on a button
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I have implemented a user following mechanism through JavaScript Embedded Ruby which sends requests asynchronously to the server without leaving the page:  

    $("#follow_form").html("<%= escape_javascript(render('users/unfollow')) %>")
    $("#followers").html('<%= @user.followers.count %>')


In the event a user double clicks on the follow button (combined with low server response times), the system sends multiple requests to the server. As a consequence, the current user follows the other user twice and @user.followers.count is increased by +2. 

How can I avoid a user being followed twice by the same user? 
In other words, how can I implement a "Fat finger" control so that my app only sends one request in case the user double clicks several times the follow button?

Looking forward,
Bart