jquery.hoverIntent.js

/* jshint forin:true, noarg:true, noempty:true, eqeqeq:true, bitwise:true, strict:true, undef:true, unused:true, curly:true, browser:true, devel:true, jquery:true, indent:4, maxerr:50 */

/**
* hoverIntent is similar to jQuery's built-in "hover" function except that
* instead of firing the onMouseOver event immediately, hoverIntent checks
* to see if the user's mouse has slowed down (beneath the sensitivity
* threshold) before firing the onMouseOver event.
* 
* hoverIntent r6 fork // 2012.07.03 // jQuery 1.7+
* <http://cherne.net/brian/resources/jquery.hoverIntent.html>
* 
* hoverIntent is currently available for use in all personal or commercial 
* projects under both MIT and GPL licenses. This means that you can choose 
* the license that best suits your project, and use it accordingly.
* 
* // basic usage (just like .hover) receives onMouseOver and onMouseOut functions
* $("ul li").hoverIntent( showNav , hideNav );
* 
* // advanced usage receives configuration object only
* $("ul li").hoverIntent({
*	sensitivity: 7, // number = sensitivity threshold (must be 1 or higher)
*	interval: 100,   // number = milliseconds of polling interval
*	over: showNav,  // function = onMouseOver callback (required)
*	timeout: 0,   // number = milliseconds delay before onMouseOut function call
*	out: hideNav,    // function = onMouseOut callback (required)
*	selector: null // string = subSelector for use with delegated event binding. (Like jQuery.on() syntax.)
* });
* 
* @param  f  onMouseOver function || An object with configuration options
* @param  g  onMouseOut function  || Nothing (use configuration options object)
* @author    Brian Cherne brian(at)cherne(dot)net
*/
(function ($) {

	"use strict";

	$.fn.hoverIntent = function (f, g) {
		
		// default configuration options
		var cfg = {
			sensitivity: 7,
			interval: 100,
			timeout: 0,
			selector: null
		};
		
		// 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
			// regarding the ( cX + cY ) > 0  check: 
			//   clicking in chrome on a selectbox triggered a track event with 0x0
			//   it's very unlikely that a human would trigger a 0x0 event
			if ( (cX + cY) > 0 && ( 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) {
			
			// 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); 
			}

			// if e.type == "mouseenter"
			if (e.type === "mouseenter") {
				// 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 == "mouseleave"
			} 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
		if (cfg.selector === null) {
			return this.bind( 'mouseenter mouseover', handleHover ).bind( 'mouseleave mouseout', handleHover );
		}
		else {
			return this.on( 'mouseenter mouseleave mouseover mouseout', cfg.selector, handleHover );
		}
	};
	
})(jQuery);