How to find a reason AngularJS “Argument ‘MyCtrl’ is not a function, got undefined”

The question:

When AngularJS crashes with an error “Argument ‘MyCtrl’ is not a function, got undefined” it’s may be little bit challenging to find a reason why.

Here I want to make a kind of a “check list”, what should you check when got an error

The Solutions:

Below are the methods you can try. The first solution is probably the best. Try others if the first one doesn’t work. Senior developers aren’t just copying/pasting – they read the methods carefully & apply them wisely to each case.

Method 1

  1. Is file with ‘MyCtrl’ connected via html? (check twice if you concat or uglify your files)
<script src='path/to/controllers.js'></script>
  1. Is ‘MyCtrl’ defined correctly?

There are a few patterns:

app.controller('MyCtrl', ['$scope', function ($scope) {...}])

app.controller('MyCtrl', function ($scope) {...})

var MyCtrl = function ($scope) {...})
  1. Is ‘MyCtrl’ defined in right module?
  2. Is “MyCtrl’s” module added to app dependencies?
angular.module('app', ['app.sources']);
  1. If you define your module multiple times, you should define it in this order:

    • First define should be like
angular.module('app.sources', []);

(with [ ])

  • Subsequent defines should be like

(without [ ])

Important: Declaration order is important – definition with [ ] should go first.

  1. Check that module is defined only once.
    You may have forgotten to rename module after copy-paste. Check src for string like
angular.module('app.sources', []);
  1. Check your 'ng-app'. Better to use only one of these with name like ng-app='app' (In other words do not define multiple unnamed ngApp directives)

  2. Is your controller’s syntax correct for your AngularJS version?

(There is a difference between definition in Angular 1.0.x and 1.2.x and higher. With Angular versions greater than 1.3.x, you cannot declare a global constructor function and use it with ng-controller)

Method 2

If you’re using the ng-controller with “controller as” syntax, be sure to check that the name of the controller is correct.

My case:

//controller register    
angular.module("myApp").controller("someController", SomeController)

//in my code
<div ng-controller="SomeController as vm"></div>

Notice that I used ng-controller="SomeController as vm", where SomeController has a capital S.
It should have been with a lowercase s because that’s how I registered it.

So, check that your controller name is correct.

All methods was sourced from or, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0

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