Context.prototype.handleScroll = function()

in website/content/javascripts/book.js [285:328]
40 lines of code
9 McCabe index (conditional complexity)

  Context.prototype.handleScroll = function() {
    var triggeredGroups = {}
    var axes = {
      horizontal: {
        newScroll: this.adapter.scrollLeft(),
        oldScroll: this.oldScroll.x,
        forward: 'right',
        backward: 'left'
      },
      vertical: {
        newScroll: this.adapter.scrollTop(),
        oldScroll: this.oldScroll.y,
        forward: 'down',
        backward: 'up'
      }
    }

    for (var axisKey in axes) {
      var axis = axes[axisKey]
      var isForward = axis.newScroll > axis.oldScroll
      var direction = isForward ? axis.forward : axis.backward

      for (var waypointKey in this.waypoints[axisKey]) {
        var waypoint = this.waypoints[axisKey][waypointKey]
        var wasBeforeTriggerPoint = axis.oldScroll < waypoint.triggerPoint
        var nowAfterTriggerPoint = axis.newScroll >= waypoint.triggerPoint
        var crossedForward = wasBeforeTriggerPoint && nowAfterTriggerPoint
        var crossedBackward = !wasBeforeTriggerPoint && !nowAfterTriggerPoint
        if (crossedForward || crossedBackward) {
          waypoint.queueTrigger(direction)
          triggeredGroups[waypoint.group.id] = waypoint.group
        }
      }
    }

    for (var groupKey in triggeredGroups) {
      triggeredGroups[groupKey].flushTriggers()
    }

    this.oldScroll = {
      x: axes.horizontal.newScroll,
      y: axes.vertical.newScroll
    }
  }