Zepto.js实现fadeIn,fadeOut功能

Zepto是一个轻量级的针对现代高级浏览器的JavaScript库， 它与jquery有着类似的api。 如果你会用jquery，那么你也会用zepto。

Zepto的设计目的是提供 jQuery 的类似的API，但并不是100%覆盖 jQuery 。所以会有些jQuery的动画功能Zepto实现不了，例如fade动画，但官方提供了解决办法，

主要是通过引入两个js插件：animate.js，zepto.animate.alias.js来实现完整的动画功能：

zepto.animate.alias.js:

/**
 * zepto.animate.alias.js
 */
(function($) {
    $.extend($.fn, {
        fadeIn: function(speed, easing, complete) {
            if(typeof(speed) === 'undefined') speed = 400;
            if(typeof(easing) === 'undefined') {
                easing = 'swing';
            } else if(typeof(easing) === 'function') {
                if(typeof(complete) === 'undefined') complete = easing;
                easing = 'swing';
            }

            $(this).css({
                display: 'block',
                opacity: 0
            }).animate({
                opacity: 1
            }, speed, easing, function() {
                // complete callback
                complete && typeof(complete) === 'function' && complete();
            });

            return this;
        },
        fadeOut: function(speed, easing, complete) {
            if(typeof(speed) === 'undefined') speed = 400;
            if(typeof(easing) === 'undefined') {
                easing = 'swing';
            } else if(typeof(easing) === 'function') {
                if(typeof(complete) === 'undefined') complete = easing;
                easing = 'swing';
            }

            $(this).css({
                opacity: 1
            }).animate({
                opacity: 0
            }, speed, easing, function() {
                $(this).css('display', 'none');
                // complete callback
                complete && typeof(complete) === 'function' && complete();
            });

            return this;
        },
        fadeToggle: function(speed, easing, complete) {
            return this.each(function() {
                var el = $(this);
                el[(el.css('opacity') === 0 || el.css('display') === 'none') ? 'fadeIn' : 'fadeOut'](speed, easing, complete)
            })
        }
    })
})(Zepto);

animate.js:

(function($, undefined) {
    var prefix = '',
        eventPrefix,
        vendors = {
            Webkit: 'webkit',
            Moz: '',
            O: 'o'
        },
        testEl = document.createElement('div'),
        supportedTransforms = /^((translate|rotate|scale)(X|Y|Z|3d)?|matrix(3d)?|perspective|skew(X|Y)?)$/i,
        transform,
        transitionProperty, transitionDuration, transitionTiming, transitionDelay,
        animationName, animationDuration, animationTiming, animationDelay,
        cssReset = {}

    function dasherize(str) {
        return str.replace(/([A-Z])/g, '-$1').toLowerCase()
    }

    function normalizeEvent(name) {
        return eventPrefix ? eventPrefix + name : name.toLowerCase()
    }

    if(testEl.style.transform === undefined) $.each(vendors, function(vendor, event) {
        if(testEl.style[vendor + 'TransitionProperty'] !== undefined) {
            prefix = '-' + vendor.toLowerCase() + '-'
            eventPrefix = event
            return false
        }
    })

    transform = prefix + 'transform'
    cssReset[transitionProperty = prefix + 'transition-property'] =
        cssReset[transitionDuration = prefix + 'transition-duration'] =
        cssReset[transitionDelay = prefix + 'transition-delay'] =
        cssReset[transitionTiming = prefix + 'transition-timing-function'] =
        cssReset[animationName = prefix + 'animation-name'] =
        cssReset[animationDuration = prefix + 'animation-duration'] =
        cssReset[animationDelay = prefix + 'animation-delay'] =
        cssReset[animationTiming = prefix + 'animation-timing-function'] = ''

    $.fx = {
        off: (eventPrefix === undefined && testEl.style.transitionProperty === undefined),
        speeds: {
            _default: 400,
            fast: 200,
            slow: 600
        },
        cssPrefix: prefix,
        transitionEnd: normalizeEvent('TransitionEnd'),
        animationEnd: normalizeEvent('AnimationEnd')
    }

    $.fn.animate = function(properties, duration, ease, callback, delay) {
        if($.isFunction(duration))
            callback = duration, ease = undefined, duration = undefined
        if($.isFunction(ease))
            callback = ease, ease = undefined
        if($.isPlainObject(duration))
            ease = duration.easing, callback = duration.complete, delay = duration.delay, duration = duration.duration
        if(duration) duration = (typeof duration == 'number' ? duration :
            ($.fx.speeds[duration] || $.fx.speeds._default)) / 1000
        if(delay) delay = parseFloat(delay) / 1000
        return this.anim(properties, duration, ease, callback, delay)
    }

    $.fn.anim = function(properties, duration, ease, callback, delay) {
        var key, cssValues = {},
            cssProperties, transforms = '',
            that = this,
            wrappedCallback, endEvent = $.fx.transitionEnd,
            fired = false

        if(duration === undefined) duration = $.fx.speeds._default / 1000
        if(delay === undefined) delay = 0
        if($.fx.off) duration = 0

        if(typeof properties == 'string') {
            // keyframe animation
            cssValues[animationName] = properties
            cssValues[animationDuration] = duration + 's'
            cssValues[animationDelay] = delay + 's'
            cssValues[animationTiming] = (ease || 'linear')
            endEvent = $.fx.animationEnd
        } else {
            cssProperties = []
            // CSS transitions
            for(key in properties)
                if(supportedTransforms.test(key)) transforms += key + '(' + properties[key] + ') '
            else cssValues[key] = properties[key], cssProperties.push(dasherize(key))

            if(transforms) cssValues[transform] = transforms, cssProperties.push(transform)
            if(duration > 0 && typeof properties === 'object') {
                cssValues[transitionProperty] = cssProperties.join(', ')
                cssValues[transitionDuration] = duration + 's'
                cssValues[transitionDelay] = delay + 's'
                cssValues[transitionTiming] = (ease || 'linear')
            }
        }

        wrappedCallback = function(event) {
            if(typeof event !== 'undefined') {
                if(event.target !== event.currentTarget) return // makes sure the event didn't bubble from "below"
                $(event.target).unbind(endEvent, wrappedCallback)
            } else
                $(this).unbind(endEvent, wrappedCallback) // triggered by setTimeout

            fired = true
            $(this).css(cssReset)
            callback && callback.call(this)
        }
        if(duration > 0) {
            this.bind(endEvent, wrappedCallback)
            // transitionEnd is not always firing on older Android phones
            // so make sure it gets fired
            setTimeout(function() {
                if(fired) return
                wrappedCallback.call(that)
            }, ((duration + delay) * 1000) + 25)
        }

        // trigger page reflow so new elements can animate
        this.size() && this.get(0).clientLeft

        this.css(cssValues)

        if(duration <= 0) setTimeout(function() {
            that.each(function() {
                wrappedCallback.call(this)
            })
        }, 0)

        return this
    }

    testEl = null
})(Zepto);