hoverIntent.js

(function($){
 /* hoverIntent by Brian Cherne */
 $.fn.hoverIntent = function(f,g) {
  // default configuration options
  var cfg = {
   sensitivity: 7,
   interval: 100,
   timeout: 0
  };
  // override configuration options with user supplied object
  cfg = $.extend(cfg, g ? { over: f, out: g } : f );

  // instantiate variables
  // cX, cY = current X and Y position of mouse, updated by mousemove event
  // pX, pY = previous X and Y position of mouse, set by mouseover and polling interval
  var cX, cY, pX, pY;

  // A private function for getting mouse position
  var track = function(ev) {
   cX = ev.pageX;
   cY = ev.pageY;
  };

  // A private function for comparing current and previous mouse position
  var compare = function(ev,ob) {
   ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
   // compare mouse positions to see if they've crossed the threshold
   if ( ( Math.abs(pX-cX) + Math.abs(pY-cY) ) < cfg.sensitivity ) {
    $(ob).unbind("mousemove",track);
    // set hoverIntent state to true (so mouseOut can be called)
    ob.hoverIntent_s = 1;
    return cfg.over.apply(ob,[ev]);
   } else {
    // set previous coordinates for next time
    pX = cX; pY = cY;
    // use self-calling timeout, guarantees intervals are spaced out properly (avoids JavaScript timer bugs)
    ob.hoverIntent_t = setTimeout( function(){compare(ev, ob);} , cfg.interval );
   }
  };

  // A private function for delaying the mouseOut function
  var delay = function(ev,ob) {
   ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t);
   ob.hoverIntent_s = 0;
   return cfg.out.apply(ob,[ev]);
  };

  // A private function for handling mouse 'hovering'
  var handleHover = function(e) {
   // next three lines copied from jQuery.hover, ignore children onMouseOver/onMouseOut
   var p = (e.type == "mouseover" ? e.fromElement : e.toElement) || e.relatedTarget;
   while ( p && p != this ) { try { p = p.parentNode; } catch(e) { p = this; } }
   if ( p == this ) { return false; }

   // copy objects to be passed into t (required for event object to be passed in IE)
   var ev = jQuery.extend({},e);
   var ob = this;

   // cancel hoverIntent timer if it exists
   if (ob.hoverIntent_t) { ob.hoverIntent_t = clearTimeout(ob.hoverIntent_t); }

   // else e.type == "onmouseover"
   if (e.type == "mouseover") {
    // set "previous" X and Y position based on initial entry point
    pX = ev.pageX; pY = ev.pageY;
    // update "current" X and Y position based on mousemove
    $(ob).bind("mousemove",track);
    // start polling interval (self-calling timeout) to compare mouse coordinates over time
    if (ob.hoverIntent_s != 1) { ob.hoverIntent_t = setTimeout( function(){compare(ev,ob);} , cfg.interval );}

   // else e.type == "onmouseout"
   } else {
    // unbind expensive mousemove event
    $(ob).unbind("mousemove",track);
    // if hoverIntent state is true, then call the mouseOut function after the specified delay
    if (ob.hoverIntent_s == 1) { ob.hoverIntent_t = setTimeout( function(){delay(ev,ob);} , cfg.timeout );}
   }
  };

  // bind the function to the two event listeners
  return this.mouseover(handleHover).mouseout(handleHover);
 };
 
})(jQuery);