[javascript] "Uncaught TypeError: undefined is not a function" - Beginner Backbone.js Application

I'm setting up a pretty simple app with backbone, and I'm getting an error.

Uncaught TypeError: undefined is not a function example_app.js:7
ExampleApp.initialize example_app.js:7
(anonymous function)

This is where the error is showing up in Chrome Inspector (init file - example_app.js):

var ExampleApp = {
  Models: {},
  Collections: {},
  Views: {},
  Routers: {},
  initialize: function() {
    var tasks = new ExampleApp.Collections.Tasks(data.tasks);
    new ExampleApp.Routers.Tasks({ tasks: tasks });
    Backbone.history.start();
  }
};

Here's my tasks index.haml file

- content_for :javascript do
  - javascript_tag do
    ExampleApp.initialize({ tasks: #{raw @tasks.to_json} });

= yield :javascript

models / task.js

var Task = Backbone.Model.extend({});

collections / tasks.js

var Tasks = Backbone.Collection.extend({
    model: Task,
    url: '/tasks'
});

routers / tasks.js

ExampleApp.Routers.Tasks = Backbone.Router.extend({
    routes: {
        "": "index"
    },

    index: function() {
        alert('test');
        // var view = new ExampleApp.Views.TaskIndex({ collection: ExampleApp.tasks });
        // $('body').html(view.render().$el);
    }
});

And here's proof that I'm calling all of the files (I think):

<script src="/assets/jquery.js?body=1" type="text/javascript"></script>
<script src="/assets/jquery_ujs.js?body=1" type="text/javascript"></script>
<script src="/assets/jquery-ui.js?body=1" type="text/javascript"></script>
<script src="/assets/underscore.js?body=1" type="text/javascript"></script>
<script src="/assets/backbone.js?body=1" type="text/javascript"></script>
<script src="/assets/backbone-support/support.js?body=1" type="text/javascript"></script>
<script src="/assets/backbone-support/composite_view.js?body=1" type="text/javascript"></script>
<script src="/assets/backbone-support/swapping_router.js?body=1" type="text/javascript"></script>
<script src="/assets/backbone-support.js?body=1" type="text/javascript"></script>
<script src="/assets/example_app.js?body=1" type="text/javascript"></script>
<script src="/assets/easing.js?body=1" type="text/javascript"></script>
<script src="/assets/modernizr.js?body=1" type="text/javascript"></script>
<script src="/assets/models/task.js?body=1" type="text/javascript"></script>
<script src="/assets/collections/tasks.js?body=1" type="text/javascript"></script>
<script src="/assets/views/task_view.js?body=1" type="text/javascript"></script>
<script src="/assets/views/tasks.js?body=1" type="text/javascript"></script>
<script src="/assets/views/tasks_index.js?body=1" type="text/javascript"></script>
<script src="/assets/routers/tasks.js?body=1" type="text/javascript"></script>
<script src="/assets/tasks/index.js?body=1" type="text/javascript"></script>
<script src="/assets/tasks/task.js?body=1" type="text/javascript"></script>
<script src="/assets/application.js?body=1" type="text/javascript"></script>

Any ideas would be great. Thanks!

I have occurred the same error look following example-

async.waterfall([function(waterCB) {
    waterCB(null);
}, function(**inputArray**, waterCB) {
    waterCB(null);
}], function(waterErr, waterResult) {
    console.log('Done');
});

In the above waterfall function, I am accepting inputArray parameter in waterfall 2nd function. But this inputArray not passed in waterfall 1st function in waterCB.

Cheak your function parameters Below are a correct example.

async.waterfall([function(waterCB) {
    waterCB(null, **inputArray**);
}, function(**inputArray**, waterCB) {
    waterCB(null);
}], function(waterErr, waterResult) {
    console.log('Done');
});

Thanks

[Joke mode on]

You can fix this by adding this:

https://github.com/donavon/undefined-is-a-function

import { undefined } from 'undefined-is-a-function';
// Fixed! undefined is now a function.

[joke mode off]