zui/src/js/scrollspy.js

一个基于 Bootstrap 深度定制开源前端实践方案，帮助你快速构建现代跨屏应用。

/* ========================================================================
 * Bootstrap: scrollspy.js v3.0.3
 * http://getbootstrap.com/javascript/#scrollspy
 *  
 * ZUI: The file has been changed in ZUI. It will not keep update with the
 * Bootsrap version in the future.
 * http://zui.sexy
 * ========================================================================
 * Copyright 2011-2014 Twitter, Inc.
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 * ======================================================================== */


+ function($) {
    'use strict';

    // SCROLLSPY CLASS DEFINITION
    // ==========================

    var zuiname = 'zui.scrollspy'

    function ScrollSpy(element, options) {
        var href
        var process = $.proxy(this.process, this)

        this.$element = $(element).is('body') ? $(window) : $(element)
        this.$body = $('body')
        this.$scrollElement = this.$element.on('scroll.' + zuiname + '.data-api', process)
        this.options = $.extend({}, ScrollSpy.DEFAULTS, options)
        if(!this.selector) this.selector = (this.options.target || ((href = $(element).attr('href')) && href.replace(/.*(?=#[^\s]+$)/, '')) //strip for ie7
            || '') + ' .nav li > a'
        this.offsets = $([])
        this.targets = $([])
        this.activeTarget = null

        this.refresh()
        this.process()
    }

    ScrollSpy.DEFAULTS = {
        offset: 10
    }

    ScrollSpy.prototype.refresh = function() {
        var offsetMethod = this.$element[0] == window ? 'offset' : 'position'

        this.offsets = $([])
        this.targets = $([])

        var self = this
        var $targets = this.$body
            .find(this.selector)
            .map(function() {
                var $el = $(this)
                var href = $el.data('target') || $el.attr('href')
                var $href = /^#./.test(href) && $(href)

                return($href && $href.length && $href.is(':visible') && [
                    [$href[offsetMethod]().top + (!$.isWindow(self.$scrollElement.get(0)) && self.$scrollElement.scrollTop()), href]
                ]) || null
            })
            .sort(function(a, b) {
                return a[0] - b[0]
            })
            .each(function() {
                self.offsets.push(this[0])
                self.targets.push(this[1])
            })
    }

    ScrollSpy.prototype.process = function() {
        var scrollTop = this.$scrollElement.scrollTop() + this.options.offset
        var scrollHeight = this.$scrollElement[0].scrollHeight || this.$body[0].scrollHeight
        var maxScroll = scrollHeight - this.$scrollElement.height()
        var offsets = this.offsets
        var targets = this.targets
        var activeTarget = this.activeTarget
        var i

        if(scrollTop >= maxScroll) {
            return activeTarget != (i = targets.last()[0]) && this.activate(i)
        }

        if(activeTarget && scrollTop <= offsets[0]) {
            return activeTarget != (i = targets[0]) && this.activate(i)
        }

        for(i = offsets.length; i--;) {
            activeTarget != targets[i] && scrollTop >= offsets[i] && (!offsets[i + 1] || scrollTop <= offsets[i + 1]) && this.activate(targets[i])
        }
    }

    ScrollSpy.prototype.activate = function(target) {
        this.activeTarget = target

        $(this.selector)
            .parentsUntil(this.options.target, '.active')
            .removeClass('active')

        var selector = this.selector +
            '[data-target="' + target + '"],' +
            this.selector + '[href="' + target + '"]'

        var active = $(selector)
            .parents('li')
            .addClass('active')

        if(active.parent('.dropdown-menu').length) {
            active = active
                .closest('li.dropdown')
                .addClass('active')
        }

        active.trigger('activate.' + zuiname)
    }


    // SCROLLSPY PLUGIN DEFINITION
    // ===========================

    var old = $.fn.scrollspy

    $.fn.scrollspy = function(option) {
        return this.each(function() {
            var $this = $(this)
            var data = $this.data(zuiname)
            var options = typeof option == 'object' && option

            if(!data) $this.data(zuiname, (data = new ScrollSpy(this, options)))
            if(typeof option == 'string') data[option]()
        })
    }

    $.fn.scrollspy.Constructor = ScrollSpy


    // SCROLLSPY NO CONFLICT
    // =====================

    $.fn.scrollspy.noConflict = function() {
        $.fn.scrollspy = old
        return this
    }


    // SCROLLSPY DATA-API
    // ==================

    $(window).on('load', function() {
        $('[data-spy="scroll"]').each(function() {
            var $spy = $(this)
            $spy.scrollspy($spy.data())
        })
    })

}(jQuery);