function throttle(fn, threshhold, scope) {

  threshhold || (threshhold = 250);

  var last,

      deferTimer;

  return function () {

    var context = scope || this;

    var now = +new Date,

        args = arguments;

    if (last && now < last + threshhold) {

      // hold on to it

      clearTimeout(deferTimer);

      deferTimer = setTimeout(function () {

        last = now;

        fn.apply(context, args);

      }, threshhold);

    } else {

      last = now;

      fn.apply(context, args);

    }

  };

}

​

var flip = -1,

    pre = $('pre');

$('body').on('mousemove', throttle(function (event) {

  pre.append(((flip *= -1) > 0 ? 'tick' : 'tock') + '\n');

}, 1000));