Changing the interval of SetInterval while it's running

Question

You could use an anonymous function:

var counter = 10;
var myFunction = function(){
    clearInterval(interval);
    counter *= 10;
    interval = setInterval(myFunction, counter);
}
var interval = setInterval(myFunction, counter);

UPDATE: As suggested by A. Wolff, use setTimeout to avoid the need for clearInterval.

var counter = 10;
var myFunction = function() {
    counter *= 10;
    setTimeout(myFunction, counter);
}
setTimeout(myFunction, counter);

Use setTimeout() instead. The callback would then be responsible for firing the next timeout, at which point you can increase or otherwise manipulate the timing.

EDIT

Here's a generic function you can use to apply a "decelerating" timeout for ANY function call.

function setDeceleratingTimeout(callback, factor, times)
{
    var internalCallback = function(tick, counter) {
        return function() {
            if (--tick >= 0) {
                window.setTimeout(internalCallback, ++counter * factor);
                callback();
            }
        }
    }(times, 0);

    window.setTimeout(internalCallback, factor);
};

// console.log() requires firebug    
setDeceleratingTimeout(function(){ console.log('hi'); }, 10, 10);
setDeceleratingTimeout(function(){ console.log('bye'); }, 100, 10);

I like this question - inspired a little timer object in me:

window.setVariableInterval = function(callbackFunc, timing) {
  var variableInterval = {
    interval: timing,
    callback: callbackFunc,
    stopped: false,
    runLoop: function() {
      if (variableInterval.stopped) return;
      var result = variableInterval.callback.call(variableInterval);
      if (typeof result == 'number')
      {
        if (result === 0) return;
        variableInterval.interval = result;
      }
      variableInterval.loop();
    },
    stop: function() {
      this.stopped = true;
      window.clearTimeout(this.timeout);
    },
    start: function() {
      this.stopped = false;
      return this.loop();
    },
    loop: function() {
      this.timeout = window.setTimeout(this.runLoop, this.interval);
      return this;
    }
  };

  return variableInterval.start();
};

Example use

var vi = setVariableInterval(function() {
  // this is the variableInterval - so we can change/get the interval here:
  var interval = this.interval;

  // print it for the hell of it
  console.log(interval);

  // we can stop ourselves.
  if (interval>4000) this.stop();

  // we could return a new interval after doing something
  return interval + 100;
}, 100);  

// we can change the interval down here too
setTimeout(function() {
  vi.interval = 3500;
}, 1000);

// or tell it to start back up in a minute
setTimeout(function() {
  vi.interval = 100;
  vi.start();
}, 60000);

I had the same question as the original poster, did this as a solution. Not sure how efficient this is ....

interval = 5000; // initial condition
var run = setInterval(request , interval); // start setInterval as "run"

    function request() { 

        console.log(interval); // firebug or chrome log
        clearInterval(run); // stop the setInterval()

         // dynamically change the run interval
        if(interval>200 ){
          interval = interval*.8;
        }else{
          interval = interval*1.2;
        }

        run = setInterval(request, interval); // start the setInterval()

    }