Find Waypoint instances by DOM element

waypoint-instances.js

'use strict';

/*
 * Find Waypoint instances by DOM element
 */

var compact = require('lodash/fp/compact');
var filter = require('lodash/fp/filter');
var flatten = require('lodash/fp/flatten');
var forEach = require('lodash/fp/forEach');
var values = require('lodash/fp/values');

var $ = window.jQuery;

module.exports = {
  find: function(elements) {
    var Waypoint, context, instances, items;
    Waypoint = window.Waypoint;
    items = $(elements);
    if (items.length === 0) {
      return [];
    }
    context = Waypoint.Context.findByElement(window);
    if (!(context instanceof Waypoint.Context)) {
      return [];
    }
    instances = flatten([values(context.waypoints.horizontal), values(context.waypoints.vertical)]);
    return compact(flatten(items.map(function(index, element) {
      return filter(function(instance) {
        return instance.element === element;
      })(instances);
    }).get()));
  },
  destroy: function(instances) {
    if (instances == null) {
      instances = [];
    }
    if (instances.length === 0) {
      return;
    }
    forEach(function(instance) {
      instance.destroy();
    })(instances);
  }
};