Using TypeScript with Angular: encountering a ReferenceError stating that the System object is not defined in the System

I attempted to follow a tutorial to set up Angular 2 with TypeScript from the following link: https://angular.io/guide/quickstart

However, I encountered the following error:

ReferenceError: System is not defined System.config

I am uncertain why this error occurs.

The structure of my project looks like this:

project
|-index.hml
|-assets
    |-js
    |- jquery
    |-app
       |-app.component.js
       |-app.component.ts
       |-app.component.js.map
       |-main.js
       |-main.ts
       |-main.js.map

Answer №1

Ensure that SystemJS is included in your HTML page for your Angular2 application to function properly from the node_modules folder. The minimum requirements are:

<script src="node_modules/angular2/bundles/angular2-polyfills.js"></script>
<script src="node_modules/systemjs/dist/system.src.js"></script> <!---
<script src="node_modules/rxjs/bundles/Rx.js"></script>
<script src="node_modules/angular2/bundles/angular2.dev.js"></script>

You also need to set up SystemJS to load your compiled TypeScript files (which are actually JavaScript files with a js extension). Here's an example of how to do it:

<script>
  System.config({
    map: {
      app: 'assets/js/app'
    },
    packages: {        
      app: {
        format: 'register',
        defaultExtension: 'js'
      }
    }
  });
</script>

This configuration ensures that when you import modules starting with app/, SystemJS will load the corresponding JS file (compiled from TypeScript). For instance, running System.import('app/main'); will load the app/main.js file.

Remember, you must have already compiled your TypeScript files. Running the npm run start command automatically starts the tsc compiler in the background, compiling TypeScript files into JS files whenever changes are detected. Make sure the compiler is running and generating the necessary JS files...

Answer №2

index.html

Don't forget to include the following script references.

<script src="https://code.angularjs.org/2.0.0-beta.7/angular2-polyfills.js"></script>


<script src="https://code.angularjs.org/tools/system.js"></script>
// It's important for preventing errors.

<script src="https://code.angularjs.org/tools/typescript.js"></script>
<script src="https://code.angularjs.org/2.0.0-beta.7/Rx.js"></script>
<script src="https://code.angularjs.org/2.0.0-beta.7/angular2.min.js"></script>
<script src="https://code.angularjs.org/2.0.0-beta.7/http.min.js"></script>
<script src="https://code.angularjs.org/2.0.0-beta.7/router.dev.js"></script>

Answer №3

This post serves as a mirror to the question angular2js: Uncaught Reference Error: System is not defined

If you are working with Angular2 Seed that already has implemented injections and necessary libraries for loading, it's advisable to leverage those built-in methods.

However, if you are starting an app from scratch, feel free to include libraries as needed following the instructions provided above.

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