Angular2 Typescript app throws 404 on components when js extension not specified

Question 1

Angular2 Typescript app throws 404 on components when js extension not specified

javascript typescript angular polyfills

xlecoustillier · Dec 20, 2015 · Viewed 33.4k times · Source

Answer

Answer

You can configure the path to your app folder. In my case, I'm using angular 2 to produce a mobile version of our app and had to configure System like so:

System.config({
            paths: {
                'app/*': './js/mobile/dist/*'
            },
            packages: {        
              app: {
                format: 'register',
                defaultExtension: 'js'
              }
            }
          });
          System.import('app/main')
                .then(null, console.error.bind(console));

As you can see, I decided to map "app" to "dist" where I have my compiled js files to keep them separate from the ts files.

Question 2

I just started to play around with Angular2, and ran into a weird component file extension problem:

Let's use the 5 minutes quickstart demo from angular.io (I'll reproduce the code here for reference).

File structure

angular2-quickstart
|- app
|  |- app.component.ts
|  |- boot.ts
|
|- index.html
|- package.json
|- tsconfig.json

package.json

{
  "name": "angular2-quickstart",
  "version": "1.0.0",
  "scripts": {
    "tsc": "tsc",
    "tsc:w": "tsc -w",
    "lite": "lite-server",
    "start": "concurrent \"npm run tsc:w\" \"npm run lite\" "
  },
  "license": "ISC",
  "dependencies": {
    "angular2": "2.0.0-beta.0",
    "systemjs": "0.19.6",
    "es6-promise": "^3.0.2",
    "es6-shim": "^0.33.3",
    "reflect-metadata": "0.1.2",
    "rxjs": "5.0.0-beta.0",
    "zone.js": "0.5.10"
  },
  "devDependencies": {
    "concurrently": "^1.0.0",
    "lite-server": "^1.3.1",
    "typescript": "^1.7.3"
  }
}

tsconfig.json

{
  "compilerOptions": {
    "target": "ES5",
    "module": "system",
    "moduleResolution": "node",
    "sourceMap": true,
    "emitDecoratorMetadata": true,
    "experimentalDecorators": true,
    "removeComments": false,
    "noImplicitAny": false
  },
  "exclude": [
    "node_modules"
  ]
}

app/app.component.ts

import {Component} from 'angular2/core';

@Component({
    selector: 'my-app',
    template: '<h1>My First Angular 2 App</h1>'
})
export class AppComponent { }

app/boot.ts

import {bootstrap}    from 'angular2/platform/browser'
import {AppComponent} from './app.component'

bootstrap(AppComponent);

index.html

<html>

  <head>
    <title>Angular 2 QuickStart</title>

    <!-- 1. Load libraries -->
    <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>

    <!-- 2. Configure SystemJS -->
    <script>
      System.config({
        packages: {        
          app: {
            format: 'register',
            defaultExtension: 'js'
          }
        }
      });
      System.import('app/boot')
            .then(null, console.error.bind(console));
    </script>

  </head>

  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>

</html>

This works like a charm, but exposes the whole file structure, including node_modules and the configuration, which seems like a bad idea.

So I tried to expose only the app folder. To achieve that, I did the following:

Copy the referenced javascript files in an app/scripts folder
Move the index.html in app
Change the references paths in this file
Change the lite script in package.json to lite-server --baseDir app

When running this, everything worked, except that angular2-polyfills.js returned :

Error: XHR error (404 Not Found) loading http://localhost:3000/app.component(…)
  run @ angular2-polyfills.js:138
  zoneBoundFn @ angular2-polyfills.js:111
  lib$es6$promise$$internal$$tryCatch @ angular2-polyfills.js:1511
  lib$es6$promise$$internal$$invokeCallback @ angular2-polyfills.js:1523
  lib$es6$promise$$internal$$publish @ angular2-polyfills.js:1494
  lib$es6$promise$$internal$$publishRejection @ angular2-polyfills.js:1444
  (anonymous function) @ angular2-polyfills.js:243
  run @ angular2-polyfills.js:138zoneBoundFn @ angular2-polyfills.js:111
  lib$es6$promise$asap$$flush @ angular2-polyfills.js:1305

Of course, if I ask for http://localhost:3000/app.component.js the file is returned correctly.

So my question is: why doesn't the .js extension get appended to app.component, resulting in this error, where that worked when the server baseDir was the root of the project ? Did I miss some configuration option ?

Angular2 Typescript app throws 404 on components when js extension not specified

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