Troubleshooting: Unable to Load my-app Component in Angular 2 Quickstart

Delving into the world of Angular, I decided to kickstart my learning journey by following the TypeScript quickstart tutorial on their official website (https://angular.io/guide/quickstart)

I'm currently navigating through ubuntu 14.04.

Despite meticulously executing each step as instructed, no errors are popping up at the end. However, the main component "my-app" fails to load; instead, all I see is a perpetual "Loading..." message.

Here's what's displaying in my browser

The index.html:

<html>
  <head>
    <title>Angular 2 QuickStart</title>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <link rel="stylesheet" href="styles.css">
    <!-- 1. Load libraries -->
     <!-- Polyfill(s) for older browsers -->
    <script src="node_modules/core-js/client/shim.min.js"></script>
    <script src="node_modules/zone.js/dist/zone.js"></script>
    <script src="node_modules/reflect-metadata/Reflect.js"></script>
    <script src="node_modules/systemjs/dist/system.src.js"></script>
    <!-- 2. Configure SystemJS -->
    <script src="systemjs.config.js"></script>
    <script>
      System.import('app').catch(function(err){ console.error(err); });
    </script>
  </head>
  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>
</html>

app/app.component.ts:

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

Omitting the other configuration files which mirror the tutorial ones, the only adjustment made was in the tsconfig.json file:

"target": "es6",

This tweak proved necessary for functionality to ensue.

Why might the main component refuse to load? What could be causing this hiccup?

Edit: These error messages appeared in my browser console:

 2 http://localhost:3000/node_modules/systemjs/dist/system.src.js Failed to load resource: the server responded with a status of 404 (Not Found)

 systemjs.config.js:46 Uncaught TypeError: System.config is not a function

 http://localhost:3000/app/ Failed to load resource: the server responded with a status of 404 (Not Found)

 app:18 Not Found: http://localhost:3000/app
    Error loading http://localhost:3000/app(anonymous function) @ app:18

 http://localhost:3000/app/ Failed to load resource: the server responded with a status of 404 (Not Found)

Answer №1

I was faced with a similar issue and after some investigation, I managed to identify the root cause of the problem.

When I executed npm start, the browser console displayed an error message stating:

XHR error (404 Not Found) loading http://localhost:3000/app/main.js
. It dawned on me that I had a file named /app/main.ts instead of main.js.

The TypeScript files (.ts) were not being compiled into JavaScript files (.js). Upon close inspection, it was revealed that there was an extra "\" character at the end of the tsconfig.json file. This extraneous character was initially unnoticed in both Explorer and Atom until I typed tsconfig in Terminal and used the Tab key for autofill, which exposed the issue. By using the command

$ mv tsconfig.json\  tsconfig.json
, I was able to correct the filename. After this adjustment, running npm start produced the desired outcome.

Therefore, I recommend verifying all your file names in the console. Hopefully, this solution will resolve your situation as well.

Answer №3

Something seems to be missing

<base href="/"> 

in the index.html file

Your index.html file should include:

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Frontend</title>
<base href="/">
<meta name="viewport" content="width=device-width, initial-scale=1">
</head>
<body>
<app-root></app-root>
</body>
</html>

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