Changing the interval of SetInterval while it's running

Question

I have written a javascript function that uses setInterval to manipulate a string every tenth of a second for a certain number of iterations.

function timer(         


        

Answer 1

(function variableInterval() {
    //whatever needs to be done
    interval *= 2; //deal with your interval
    setTimeout(variableInterval, interval);
    //whatever needs to be done
})();

can't get any shorter