gistfile1.js

// modernizr plugin for touch detection
// mostly by jdalton.

// The catch is that Modernizr.touch cannot be checked before the first mousedown/click/touch of the user


// lazily add listeners
// http://dl.dropbox.com/u/513327/touch_event/test2.html
// http://www.quirksmode.org/blog/archives/2010/02/do_we_need_touc.html#link4
(function() {
  var hasTouchEvents = false;
  
  if (!document.addEventListener){
      report(); // fail the test if IE event model
      return;
  }

  function touchstart() {
    hasTouchEvents = true;
    this.removeEventListener('mousedown', mousedown, true);
    this.removeEventListener('touchstart', touchstart, true);

    // hookup bubble phase touch event handlers
    // foo.addEventListener('touchstart', handler, false);
    report();
  }

  // use an event that is triggered just after touchstart
  function mousedown() {
    this.removeEventListener('mousedown', mousedown, true);

    // hookup regular bubble phase event handlers here
    // foo.addEventListener('click', handler, false);
    report();
  }
  
  function report(){
      Modernizr.addTest('touch',function(){ return hasTouchEvents; }); 
  }

  document.addEventListener('mousedown', mousedown, true);
  document.addEventListener('touchstart', touchstart, true);
})();

this is deprecated cuz chrome 5 is dead now.

back to an easy 'ontouchstart' in document or whatever check