Attach validators to a FormControl.
Attach validators to a FormControl with a standalone Angular component and explicit browser behavior.
import { Component, input, output } from '@angular/core';
import { bootstrapApplication } from '@angular/platform-browser';
import { FormControl, Validators, ReactiveFormsModule } from '@angular/forms';
@Component({
selector: 'app-root',
standalone: true,
imports: [ReactiveFormsModule],
template: `
<main data-ready>
<label>Name<input [formControl]="name" /></label><output>{{ name.valid ? "Valid" : "Required" }}</output>
</main>
`
})
class App {
name = new FormControl("", {nonNullable: true, validators: [Validators.required]});
}
bootstrapApplication(App).catch(console.error);Expected output EXAMPLE
The output displays “Required”. Enter “Ada” into the “Name” control. The output displays “Valid”.
Details
Use this main.ts in a modern Angular 22 standalone project with an <app-root></app-root> element in index.html. It includes bootstrapApplication. The test uses Angular ahead-of-time compilation with strict template checks, then checks the rendered behavior in Chromium.
Tested on Ubuntu 24.04.3 LTS · · Node.js v24.15.0; Chromium 141.0.7390.37 · @angular/common 22.2.3; @angular/compiler 22.2.3; @angular/core 22.2.3; @angular/forms 22.2.3; @angular/platform-browser 22.2.3; esbuild 0.28.2; playwright 1.56.0; rxjs 7.8.2; @angular/compiler-cli 22.2.3; typescript 6.0.3
Test inputs, results and environment
The exact published code ran in a dedicated Linux test container with prepared inputs. Dedicated test container, external networking disabled, read-only root, temporary per-example working directory. Browser network requests are blocked. Fixtures and output records are isolated from the application database. Testing covers this example and its stated checks, not every input, operating system, or runtime version. The Linux container shares its host's kernel; this is not a native Windows test.
- Architecture / host kernel
- x86_64 / 6.18.54.1-microsoft-standard-WSL2
- Snippet identity / locale
- uid=65534, gid=65534 (unprivileged) / C.UTF-8
- Interpreter invocation
Compile with Angular ngc (strict TypeScript and strictTemplates); bundle the exact published component with esbuild; mount it in Chromium and execute browser assertions- Container image ID
sha256:c9bce90110f636fe04907469a37e9c8ac888171fd569cbf87101743ec7cdf099- Code SHA-256
bb59194098cebaeff94a8ebec7ed80ba9627bb914d865c4c21bc91747e48ffd5- Dependencies
- @angular/common 22.2.3; @angular/compiler 22.2.3; @angular/core 22.2.3; @angular/forms 22.2.3; @angular/platform-browser 22.2.3; esbuild 0.28.2; playwright 1.56.0; rxjs 7.8.2; @angular/compiler-cli 22.2.3; typescript 6.0.3
Test input setup
These are the prepared inputs used by the test harness. See Details above for the prerequisites and how to run this example.
The harness supplies index.html and mounts the published component with locally installed, pinned dependencies.
Observed standard output
Expected output describes the rendered page. The standard-output record below is the browser test harness receipt; the additional assertions check the result and interactions.
Attach validators to a FormControl: browser checks passed.
Exit code: 0. Standard error: empty. Validation: Shape/content assertions. System-dependent values above are one recorded run.
Additional assertions that passed
Checks recorded by the test harness. Where Python assertions are shown, browser cases use Playwright and simulator cases may inspect pin transitions: result.stdout is captured output, work is the temporary directory, and Path is pathlib.Path. The harness also imports json and csv.
await text('output','Required'); await page.getByLabel('Name').fill('Ada'); await text('output','Valid');