Question

I’m making a site where a user repeatedly clicks a button to increase his/her score. In order to prevent people cheating, I want to measure the amount of time between each click, and if they are clicking inhumanly fast and there is very little time between clicks, I want a CAPTCHA or something to come up.

How would I measure the time between clicks?

Answer 1

My suggestion would look like:

$('button').click((function() {
    var history = [],
        last    = +new Date();

    return function(e) {
        history.push(e.timeStamp - last);

        console.log(history[history.length - 1]);
        last = e.timeStamp;
    };
}()));

This will output & store the difference between two clicks in miliseconds. You could use the history array to get an average value and check if that is below 50ms or something.

Demo: http://jsfiddle.net/TxKjT/

Demo with average check: http://jsfiddle.net/TxKjT/2/