[$injector:nomod] Module not found

The error [$injector:nomod] Module not found is another common issue encountered in AngularJS applications. It occurs when AngularJS tries to inject a module, but it cannot find it. This error typically points to issues related to missing or improperly referenced modules.

Here’s a detailed step-by-step breakdown to help you understand this error and how to resolve it:

Step 1: Understanding the Error

The [$injector:nomod] Module not found error indicates that AngularJS is unable to find the module that you are trying to inject. This could happen when:

• The module is not defined or included in your project.
• The module name is misspelled or incorrectly referenced.
• The module is not loaded in the correct order.
• There is a problem in the module loading process (e.g., broken script reference).

When you define a module in AngularJS using angular.module('moduleName', []), AngularJS will try to find and load this module at runtime. If it cannot find the module, the $injector:nomod error occurs.

Step 2: Verify Module Definition

First, make sure that the module you are trying to inject is correctly defined.

For example, if you are using a module called myModule, ensure that it is defined like this:

angular.module('myModule', []);

If the module is supposed to have dependencies, make sure they are properly listed:

angular.module('myModule', ['dependencyModule1', 'dependencyModule2']);

If the module is not defined at all or the definition is incorrect, AngularJS will not be able to instantiate it and you will see this error.

Step 3: Check the Order of Script Loading

AngularJS modules need to be loaded in the correct order. If the module you are trying to inject depends on other modules, make sure the dependent modules are loaded first.

For example, ensure that your HTML script tags are in the right order:

<script src="angular.min.js"></script>
<script src="dependencyModule1.js"></script>
<script src="dependencyModule2.js"></script>
<script src="myModule.js"></script>
<script src="app.js"></script>

If myModule.js depends on dependencyModule1.js, dependencyModule1.js must be loaded first.

Step 4: Check for Typo in Module Name

One of the most common reasons for this error is a typo in the module name. The module name is case-sensitive and needs to match exactly wherever it is referenced in the code.

For example, if the module is defined as:

angular.module('myModule', []);

You must inject it using the same exact name:

angular.module('myModule', ['someOtherModule']);

If you accidentally reference it with a different name, like angular.module('MyModule'), AngularJS will not be able to find the module and will throw the [$injector:nomod] Module not found error.

Step 5: Verify All Dependencies Are Loaded

If your module depends on other modules, ensure that those dependencies are correctly loaded. This includes both AngularJS core modules (like ngRoute, ngResource, etc.) and any custom modules you’ve created.

For example:

angular.module('myModule', ['ngRoute', 'ngResource']);

Make sure that both ngRoute and ngResource are loaded before myModule.js. If any of these dependencies are missing or not loaded properly, AngularJS will not be able to find the module and throw the error.

Step 6: Check for Dynamic Module Creation

In some cases, modules might be created dynamically at runtime based on certain conditions or configurations. If the module is not properly created before it is injected, the [$injector:nomod] error will be thrown.

For example:

if (someCondition) {
  angular.module('dynamicModule', []);
}

If someCondition is not true, the module dynamicModule will not exist, and any code that tries to inject it will fail.

Step 7: Ensure Correct Path to Script Files

If you are loading your JavaScript files from a different location (e.g., a CDN or a local file), ensure that the path to the file is correct.

For example:

<script src="path/to/angular.min.js"></script>
<script src="path/to/myModule.js"></script>

If the path to myModule.js is incorrect or the file is not present at that location, AngularJS will not be able to load the module and will throw the [$injector:nomod] error.

Step 8: Check for Asynchronous Module Loading

If you are using tools like RequireJS or other module loaders, ensure that your module dependencies are loaded asynchronously in the correct order. These loaders often require additional configuration to ensure modules are loaded before AngularJS attempts to inject them.

For example, with RequireJS, you would need to configure the dependencies like this:

require(['angular', 'dependencyModule1', 'myModule'], function (angular, dependencyModule1, myModule) {
  angular.bootstrap(document, ['myModule']);
});

If the modules are not loaded in the correct order, AngularJS may fail to find them during bootstrapping, causing the error.

Step 9: Debugging the Issue

Use browser developer tools (F12) to check the console for any related errors or warnings that could give more context about the issue. If there are missing files or incorrectly referenced modules, you might see additional error messages in the console.

Also, check the network tab to see if the JavaScript files are being loaded properly. If you notice that a script is missing or not loading, it could indicate that the module is not found.

Step 10: Review the Application’s AngularJS Bootstrapping

In some cases, the error can occur if AngularJS is not properly bootstrapped. If you are manually bootstrapping AngularJS using angular.bootstrap(), ensure that the module is correctly referenced.

For example:

angular.bootstrap(document, ['myModule']);

If myModule is not correctly defined, this could lead to the [$injector:nomod] error.

Step 11: Fix the Issue

Once you’ve identified the root cause, you can fix it by:

1. Ensuring all modules are correctly defined and loaded.
2. Checking for typos and case-sensitive mismatches in module names.
3. Ensuring dependencies are loaded in the correct order.
4. Verifying paths to script files are correct.
5. Checking the network tab and browser console for any additional errors.
6. Reviewing the bootstrapping process to ensure that AngularJS is initialized properly.