The Angular 2 bootstrap function is throwing an error stating that the argument type AppComponent cannot be assigned to the parameter type Type

Presenting my very first Angular 2 application with a simple Hello World example, inspired by the Angular 2 quick start guide.

import {Component} from 'angular2/core';
import {bootstrap} from 'angular2/platform/browser';
@Component({
    selector: 'ng2-app',
    template: '<h1>My first Angular 2 App</h1>'
})
export class AppComponent { }


bootstrap(AppComponent);

Although the application functions smoothly with npm start, my IntelliJ IDE is flagging an error at the line containing bootstrap(AppComponent).

The argument type AppComponent is not assignable to the parameter type Type

https://i.sstatic.net/5xWna.png

Upon examining the declaration of the bootstrap function, it seems that AppComponent should extend Type.

export declare function bootstrap(appComponentType: Type, customProviders?: Array<any>): Promise<ComponentRef>;

My query is:

Is it a standard practice for Angular components to inherit from Type?

javascriptangulartypescriptintellij-idea

Answer №1

While working in IntelliJ 2016.1.2 with the Angular quickstart demo, I came across a solution that helped me set the necessary options in the IDE:

https://i.sstatic.net/xyz123.png

Answer №2

To resolve the issue, simply include the comment/annotation as demonstrated below:

// @ts-ignore
bootstrap(AppComponent);

Answer №3

Unfortunately, the previous solution provided did not solve my issue. However, after following the suggestions mentioned in the comments above, I was able to successfully resolve the problem.

initializeApp(<any>MainComponent);

My development environment is currently Intellij 14.1.5

Answer №4

It is important to note that AppComponent should extend Type. Make sure to implement the following:

// import necessary libraries
import { Component, Type } from '@angular2/core';

@Component({
// component configuration
...
...
})
export class AppComponent extends Type {}

By following this convention, you will align with Angular 2 standards for AppComponent, which is crucial for bootstrapping.

It is interesting to see why the ng2 tutorials do not emphasize this aspect. Perhaps, to simplify the initial learning process, they avoid the extends directive.

This setup should work seamlessly in WebStorm/IntelliJ.

Edit: Another solution is to upgrade to Webstorm v2016.2, which is stable as of now.

Answer №5

In my opinion, constantly changing the code just to satisfy WebStorm / IntelliJ's complaints is not a practical solution. Instead, I have opted to disable IntelliJ's operations on TypeScript since I have a separate bundling and compiling process. This can be done by navigating to Settings -> Languages -> TypeScript and unchecking the relevant options. If you already have these options unchecked, you can try toggling them on and off.

It seems that this workaround is somewhat inconsistent. For instance, after renaming classes using the IDE (SHIFT + F6), errors may still persist. However, repeating the above steps has successfully resolved these issues for me.

This experience is based on using IntelliJ 15.0.2.

Answer №6

For me, utilizing the solution provided above has proven to be effective with Webstorm 2016.1.3

To implement this solution, navigate to Settings -> Language & Frameworks -> TypeScript: Enable TypeScript, Utilize tsconfig.json

Side note: This solution is identical to the one mentioned earlier for the previous version of Webstorm (2016.1.3)

Answer №7

This issue arises when the TypeScript compiler is not activated in your IDE. To resolve this, you should ensure that the TypeScript compiler is enabled.

To enable the TypeScript compiler in WebStorm:

Go to the upper left WebStorm menu => Select Preferences => Navigate to Languages & Frameworks => Click on TypeScript => Check the box to Enable TypeScript compiler => Make sure to use the tsconfig.json option => Click "Ok" to apply the changes.

https://i.sstatic.net/Yyk2X.png

Answer №8

When working with the latest angular2 router, I encountered a situation where I needed to...

bootstrap(AppComponent [
    <any>APP_ROUTER_PROVIDERS
    ]).catch((err:any) => console.error(err));

It's important to note that the 'any' type is applied to APP_ROUTER_PROVIDERS and not to AppComponent.

Answer №9

//ignore TypeScriptValidateTypes It solved the issue for me on WebStorm.

Interestingly, I tried opening my project in IntelliJ instead and the error was not present.

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