javascript - Backbone.js - Not able to trigger an event in a collection -

i'm new javascript , backbone , came across error.

router = backbone.router.extend({      routes: {         ":albumid": "load"      },      load: function (albumid) {         if (controller.collectioninitialized == true) {             console.log("reset");             album.trigger("clear");         }          var album = new album([], {             title: albumid         });          controller.trigger("collectioninit");         controller.trigger("switchalbum", albumid);     } });  controller = backbone.model.extend({      currentalbum: "",     collectioninitialized: false,      initialize: function () {         console.log("controller initialized");         this.on("switchalbum", function (newalbum) {             this.currentalbum = newalbum;          });          this.on("collectioninit", function () {             this.collectioninitialized = true;         });     } });  album = backbone.collection.extend({      initialize: function (models, options) {         this.on("clear", this.clear);     },     clear: function () {         this.reset();         this.off();     }  }); 

i error: unable property 'trigger' of undefined or null reference. if statement makes sure album exists before triggering clear. tried calling album.reset() directly got same error. guess it's kind of scoping problem, please point me in right direction?

edit

re-reading code, assuming controller valid instance , exists, , assuming controller.collectioninitialized set true, calling method trigger on variable album value null.

using js hoisting rules, load function have written

load: function(albumid) {      var album = null;      if (controller.collectioninitialized == true) {         console.log("reset");         album.trigger("clear");     }      album = new album([], { title: albumid });     controller.trigger("collectioninit");     controller.trigger("switchalbum", albumid); } 

maybe, above re-writing makes clear if controller.collectioninitialized true, album local variable , reset null each time load function called.

what ever mechanism used enable global access controller, use same means enable global access album. not re-declare album local function.

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it may read more javascript variable , function hoisting.