scrollspy.js

/* ========================================================================
 * Bootstrap: scrollspy.js v3.1.1
 * http://getbootstrap.com/javascript/#scrollspy
 * ========================================================================
 * Copyright 2011-2014 Twitter, Inc.
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
 * ======================================================================== */


+function () { 'use strict';

  (function (o_o) {
    typeof define  == 'function' && define.amd ? define(['jquery'], o_o) :
    typeof exports == 'object' ? o_o(require('jquery')) : o_o(jQuery)
  })(function ($) {

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

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

      this.$body          = $('body')
      this.$scrollElement = $(element).is('body') ? $(window) : $(element)
      this.options        = $.extend({}, ScrollSpy.DEFAULTS, options)
      this.selector       = (this.options.target || '') + ' .nav li > a'
      this.offsets        = []
      this.targets        = []
      this.activeTarget   = null
      this.scrollHeight   = 0

      this.$scrollElement.on('scroll.bs.scrollspy', process)
      this.refresh()
      this.process()
    }

    ScrollSpy.VERSION  = '3.1.1'

    ScrollSpy.DEFAULTS = {
      offset: 10
    }

    ScrollSpy.prototype.getScrollHeight = function () {
      return this.$scrollElement[0].scrollHeight || Math.max(this.$body[0].scrollHeight, document.documentElement.scrollHeight)
    }

    ScrollSpy.prototype.refresh = function () {
      var offsetMethod = 'offset'
      var offsetBase   = 0

      if (!$.isWindow(this.$scrollElement[0])) {
        offsetMethod = 'position'
        offsetBase   = this.$scrollElement.scrollTop()
      }

      this.offsets = []
      this.targets = []
      this.scrollHeight = this.getScrollHeight()

      var self     = this

      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 + offsetBase, 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.$scrollElement.scrollTop() + this.options.offset
      var scrollHeight = this.getScrollHeight()
      var maxScroll    = this.options.offset + scrollHeight - this.$scrollElement.height()
      var offsets      = this.offsets
      var targets      = this.targets
      var activeTarget = this.activeTarget
      var i

      if (this.scrollHeight != scrollHeight) {
        this.refresh()
      }

      if (scrollTop >= maxScroll) {
        return activeTarget != (i = targets[targets.length - 1]) && 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.bs.scrollspy')
    }


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

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

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

    var old = $.fn.scrollspy

    $.fn.scrollspy             = Plugin
    $.fn.scrollspy.Constructor = ScrollSpy


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

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


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

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

  })

}();