Using System.import in my code is triggering a cascade of errors in my console

Question

Using System.import in my code is triggering a cascade of errors in my console

I incorporate the System module in my component.

export class LoginComponent {
    constructor() {
        System.import('app/login/login.js');
    }
}

The file loads successfully, however, TypeScript compiler raises an error

Error:(10, 9) TS2304: Cannot find name 'System'.

In addition, my browser console displays

EXCEPTION: Error: Uncaught (in promise): Error: Error: http://localhost:3000/app/login/login.js detected as register but didn't execute.
        at ZoneDelegate.invoke (http://localhost:3000/node_modules/angular2/bundles/angular2-polyfills.js:332:29)
        at Object.NgZoneImpl.inner.inner.fork.onInvoke (http://localhost:3000/node_modules/angular2/bundles/angular2.dev.js:2111:31)
        at ZoneDelegate.invoke (http://localhost:3000/node_modules/angular2/bundles/angular2-polyfills.js:331:35)
        at Zone.run (http://localhost:3000/node_modules/angular2/bundles/angular2-polyfills.js:227:44)
    Error loading http://localhost:3000/app/login/login.js

Error: Uncaught (in promise): Error: Error: http://localhost:3000/app/login/login.js detected as register but didn't execute.(…)

What steps can I take to resolve this issue?

typescript angular

Answer 1

Answer №1

An issue arises due to the lack of typings for the SystemJS library.

Typically, we don't explicitly use System.import in TypeScript files since it can be handled behind the scenes. For example, when you write code like this, the TypeScript compiler will automatically convert the import statement into something compatible with SystemJS:

import {...} from 'app/login/login';

export class LoginComponent {
  constructor() {
  }
}

You may also notice that I have removed the js extension because SystemJS allows customization of the default extension for resolving modules:

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

Answer 2

An issue arises due to the lack of typings for the SystemJS library.

Typically, we don't explicitly use System.import in TypeScript files since it can be handled behind the scenes. For example, when you write code like this, the TypeScript compiler will automatically convert the import statement into something compatible with SystemJS:

import {...} from 'app/login/login';

export class LoginComponent {
  constructor() {
  }
}

You may also notice that I have removed the js extension because SystemJS allows customization of the default extension for resolving modules:

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

Answer 3

Answer №2

How can I utilize ES6 syntax to import my .js file?

Here's a simple two-step process:

Start by declaring the JS file in your vendor.d.ts

declare module 'app/login/login' { var foo:any; export = foo; }
Next, integrate it into your TypeScript code

import * as login from 'app/login/login';

Finally, compile your code using '--module system' 🌹

Answer 4

How can I utilize ES6 syntax to import my .js file?

Here's a simple two-step process:

Start by declaring the JS file in your vendor.d.ts

declare module 'app/login/login' { var foo:any; export = foo; }
Next, integrate it into your TypeScript code

import * as login from 'app/login/login';

Finally, compile your code using '--module system' 🌹

Using System.import in my code is triggering a cascade of errors in my console

Answer №1

Answer №2

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