Angular2: Error: unexpected value 'AppComponent' declared by the module 'AppModule'

Question

I'm working through the tutorial at https://angular.io/docs/ts/latest/tutorial/toh-pt2.html and get the following error after creating the array of heroes:

Error: Error: Unexpected value 'AppComponent' declared by the module 'AppModule'
    at new BaseException (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:5116:27)
    at eval (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:13274:35)
    at Array.forEach (native)
    at CompileMetadataResolver.getNgModuleMetadata (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:13261:53)
    at RuntimeCompiler._compileComponents (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:15845:51)
    at RuntimeCompiler._compileModuleAndComponents (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:15769:41)
    at RuntimeCompiler.compileModuleAsync (localhost:3000/node_modules/@angular/compiler//bundles/compiler.umd.js:15746:25)
    at PlatformRef_._bootstrapModuleWithZone (localhost:3000/node_modules/@angular/core//bundles/core.umd.js:9991:29)
    at PlatformRef_.bootstrapModule (localhost:3000/node_modules/@angular/core//bundles/core.umd.js:9984:25)
    at Object.eval (localhost:3000/app/main.js:4:53)
Evaluating localhost:3000/app/main.js
Error loading localhost:3000/app/main.js

My app.module.ts file at this point is:

import { NgModule }     from '@angular/core';
import { BrowserModule }from '@angular/platform-browser';
import { FormsModule }  from '@angular/forms';

import { AppComponent } from './app.component';

@NgModule({
    imports:        [ BrowserModule, FormsModule ],
    declarations:   [ AppComponent ],
    bootstrap:      [ AppComponent ]
})

export class AppModule {}

My app.components.ts file at this point is:

import { Component } from '@angular/core';

export class Hero {
    id: number;
    name: string;
 }

@Component ({
    selector: 'my-app',
    template: `
        <h1>{{title}}</h1>

        <h2>My Heroes</h2>
        <ul class="heroes">
            <li *ngFor="let hero of heroes">
                 <span class="badge">{{hero.id}}</span> {{hero.name}}
            </li>
         </ul>        

         <h2>{{hero.name}} details!</h2>
         <div><label>id: </label>{{hero.id}}</div>
         <div>
             <label>name: </label>
             <input [(ngModel)]="hero.name" placeholder="name">
         </div> 
         ` 
 })

const HEROES: Hero[] = [
    { id: 11, name: 'Mr. Nice' },
    { id: 12, name: 'Narco' },
    { id: 13, name: 'Bombasto' },
    { id: 14, name: 'Celeritas' },
    { id: 15, name: 'Magneta' },
    { id: 16, name: 'RubberMan' },
    { id: 17, name: 'Dynama' },
    { id: 18, name: 'Dr IQ' },
    { id: 19, name: 'Magma' },
    { id: 20, name: 'Tornado' }
];

export class AppComponent {
    title = 'Tour or Heroes';
    heroes = HEROES;
}

Everything was working up to this point. New to Angular and not sure how to debug this.

Edit:

The error occurs in (index) at:

    <!-- 2. Configure SystemJS -->
    <script src = "systemjs.config.js"></script>
    <script>
        System.import('app').catch(function(err) {
            console.error(err);
        });
    </script>
</head>

Thanks,

Answer 1

Decorators are related classes or variables which are following the declaration of the decorator.

In your code the @compoment decorator is over const HEROES and this must be over class AppComponent .

So your code should be the following:

import { Component } from '@angular/core';

export class Hero {
    id: number;
    name: string;
 }


export const HEROES: Hero[] = [
    { id: 11, name: 'Mr. Nice' },
    { id: 12, name: 'Narco' },
    { id: 13, name: 'Bombasto' },
    { id: 14, name: 'Celeritas' },
    { id: 15, name: 'Magneta' },
    { id: 16, name: 'RubberMan' },
    { id: 17, name: 'Dynama' },
    { id: 18, name: 'Dr IQ' },
    { id: 19, name: 'Magma' },
    { id: 20, name: 'Tornado' }
];


@Component ({
    selector: 'my-app',
    template: `
        <h1>{{title}}</h1>

        <h2>My Heroes</h2>
        <ul class="heroes">
            <li *ngFor="let hero of heroes">
                 <span class="badge">{{hero.id}}</span> {{hero.name}}
            </li>
         </ul>        

         <h2>{{hero.name}} details!</h2>
         <div><label>id: </label>{{hero.id}}</div>
         <div>
             <label>name: </label>
             <input [(ngModel)]="hero.name" placeholder="name">
         </div> 
         ` 
 })
export class AppComponent {
    title = 'Tour or Heroes';
    heroes = HEROES;
}

Answer 2

I'll quickly note that this error can be thrown from any manner of @Component declaration error — Ie, even @Component({}); — (note the semicolon).

If you receive this error, make sure to check that your syntax is correct.

True as of 2.0.0-rc.6.

Answer 3

when i encounter it , i check it for a long time . finally , at the end of @Component({}) ,there is one more ';'. Unknown so

Answer 4

I had this error after adding some of my components from root folder in separate folder. The problem was with using ./filename for path to templateUrl and styleUrls, after removing ./ the error was gone.

Answer 5

In my case I had declared a class just over the component class definition like below. I have moved the class MyClass definition below the export class and it worked. So I assume that export class must be the first declaration in the component file.

class MyClass {

}
export class MyComponent implements OnInit {

Answer 6

如果您在同一文件上的应用程序组件声明之前有@Injectable()类，则也可能存在此错误。