annotate libraries/jquery.hoverIntent/jquery.hoverIntent.js @ 19:fa3358dc1485 tip

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/*!
 * hoverIntent v1.9.0 // 2017.09.01 // jQuery v1.7.0+
 * http://briancherne.github.io/jquery-hoverIntent/
 *
 * You may use hoverIntent under the terms of the MIT license. Basically that
 * means you are free to use hoverIntent as long as this header is left intact.
 * Copyright 2007-2017 Brian Cherne
 */

/* hoverIntent is similar to jQuery's built-in "hover" method except that
 * instead of firing the handlerIn function immediately, hoverIntent checks
 * to see if the user's mouse has slowed down (beneath the sensitivity
 * threshold) before firing the event. The handlerOut function is only
 * called after a matching handlerIn.
 *
 * // basic usage ... just like .hover()
 * .hoverIntent( handlerIn, handlerOut )
 * .hoverIntent( handlerInOut )
 *
 * // basic usage ... with event delegation!
 * .hoverIntent( handlerIn, handlerOut, selector )
 * .hoverIntent( handlerInOut, selector )
 *
 * // using a basic configuration object
 * .hoverIntent( config )
 *
 * @param  handlerIn   function OR configuration object
 * @param  handlerOut  function OR selector for delegation OR undefined
 * @param  selector    selector OR undefined
 * @author Brian Cherne <brian(at)cherne(dot)net>
 */

;(function(factory) {
    'use strict';
    if (typeof define === 'function' && define.amd) {
        define(['jquery'], factory);
    } else if (jQuery && !jQuery.fn.hoverIntent) {
        factory(jQuery);
    }
})(function($) {
    'use strict';

    // default configuration values
    var _cfg = {
        interval: 100,
        sensitivity: 6,
        timeout: 0
    };

    // counter used to generate an ID for each instance
    var INSTANCE_COUNT = 0;

    // current X and Y position of mouse, updated during mousemove tracking (shared across instances)
    var cX, cY;

    // saves the current pointer position coordinates based on the given mousemove event
    var track = function(ev) {
        cX = ev.pageX;
        cY = ev.pageY;
    };

    // compares current and previous mouse positions
    var compare = function(ev,$el,s,cfg) {
        // compare mouse positions to see if pointer has slowed enough to trigger `over` function
        if ( Math.sqrt( (s.pX-cX)*(s.pX-cX) + (s.pY-cY)*(s.pY-cY) ) < cfg.sensitivity ) {
            $el.off(s.event,track);
            delete s.timeoutId;
            // set hoverIntent state as active for this element (permits `out` handler to trigger)
            s.isActive = true;
            // overwrite old mouseenter event coordinates with most recent pointer position
            ev.pageX = cX; ev.pageY = cY;
            // clear coordinate data from state object
            delete s.pX; delete s.pY;
            return cfg.over.apply($el[0],[ev]);
        } else {
            // set previous coordinates for next comparison
            s.pX = cX; s.pY = cY;
            // use self-calling timeout, guarantees intervals are spaced out properly (avoids JavaScript timer bugs)
            s.timeoutId = setTimeout( function(){compare(ev, $el, s, cfg);} , cfg.interval );
        }
    };

    // triggers given `out` function at configured `timeout` after a mouseleave and clears state
    var delay = function(ev,$el,s,out) {
        delete $el.data('hoverIntent')[s.id];
        return out.apply($el[0],[ev]);
    };

    $.fn.hoverIntent = function(handlerIn,handlerOut,selector) {
        // instance ID, used as a key to store and retrieve state information on an element
        var instanceId = INSTANCE_COUNT++;

        // extend the default configuration and parse parameters
        var cfg = $.extend({}, _cfg);
        if ( $.isPlainObject(handlerIn) ) {
            cfg = $.extend(cfg, handlerIn);
            if ( !$.isFunction(cfg.out) ) {
                cfg.out = cfg.over;
            }
        } else if ( $.isFunction(handlerOut) ) {
            cfg = $.extend(cfg, { over: handlerIn, out: handlerOut, selector: selector } );
        } else {
            cfg = $.extend(cfg, { over: handlerIn, out: handlerIn, selector: handlerOut } );
        }

        // A private function for handling mouse 'hovering'
        var handleHover = function(e) {
            // cloned event to pass to handlers (copy required for event object to be passed in IE)
            var ev = $.extend({},e);

            // the current target of the mouse event, wrapped in a jQuery object
            var $el = $(this);

            // read hoverIntent data from element (or initialize if not present)
            var hoverIntentData = $el.data('hoverIntent');
            if (!hoverIntentData) { $el.data('hoverIntent', (hoverIntentData = {})); }

            // read per-instance state from element (or initialize if not present)
            var state = hoverIntentData[instanceId];
            if (!state) { hoverIntentData[instanceId] = state = { id: instanceId }; }

            // state properties:
            // id = instance ID, used to clean up data
            // timeoutId = timeout ID, reused for tracking mouse position and delaying "out" handler
            // isActive = plugin state, true after `over` is called just until `out` is called
            // pX, pY = previously-measured pointer coordinates, updated at each polling interval
            // event = string representing the namespaced event used for mouse tracking

            // clear any existing timeout
            if (state.timeoutId) { state.timeoutId = clearTimeout(state.timeoutId); }

            // namespaced event used to register and unregister mousemove tracking
            var mousemove = state.event = 'mousemove.hoverIntent.hoverIntent'+instanceId;

            // handle the event, based on its type
            if (e.type === 'mouseenter') {
                // do nothing if already active
                if (state.isActive) { return; }
                // set "previous" X and Y position based on initial entry point
                state.pX = ev.pageX; state.pY = ev.pageY;
                // update "current" X and Y position based on mousemove
                $el.off(mousemove,track).on(mousemove,track);
                // start polling interval (self-calling timeout) to compare mouse coordinates over time
                state.timeoutId = setTimeout( function(){compare(ev,$el,state,cfg);} , cfg.interval );
            } else { // "mouseleave"
                // do nothing if not already active
                if (!state.isActive) { return; }
                // unbind expensive mousemove event
                $el.off(mousemove,track);
                // if hoverIntent state is true, then call the mouseOut function after the specified delay
                state.timeoutId = setTimeout( function(){delay(ev,$el,state,cfg.out);} , cfg.timeout );
            }
        };

        // listen for mouseenter and mouseleave
        return this.on({'mouseenter.hoverIntent':handleHover,'mouseleave.hoverIntent':handleHover}, cfg.selector);
    };
});