Adding the Google reCAPTCHA v2 to an Angular application

Introduction

Angular is a development platform for building WEB, mobile and desktop applications using HTML, CSS and TypeScript (JavaScript). Currently, Angular is at version 15 and Google is the main maintainer of the project.

ng-recaptcha is a simple and configurable reCAPTCHA v2 and v3 component library.

Prerequisites

Before you start, you need to install and configure the tools:

• git
• Node.js and npm
• Angular CLI
• IDE (e.g. Visual Studio Code)

Getting started

Create and configure the account on the Google reCAPTCHA

1. Let's create the account. Access the site https://www.google.com/recaptcha/ and click on the button v3 Admin Console.

2. Fill in the field Email or phone and click on the button Next to login with your Google account and if you don't have an account, just create a new account.

3. Fill in the field Label, click on the option reCAPTCHA v2, Fill in the field Domains, click on the checkbox Accept the reCAPTCHA Terms of Service and click on the button Submit.

4. Click on the button COPY SITE KEY to copy the key, in my case, the key 6LfKNi0cAAAAACeYwFRY9_d_qjGhpiwYUo5gNW5- was copied because this key will be configured in the Angular application.

5. Ready! The keys have been generated.

Create the Angular application

1. Let's create the application with the Angular base structure using the @angular/cli with the route file and the SCSS style format.

ng new angular-recaptcha-v2
? Would you like to add Angular routing? Yes
? Which stylesheet format would you like to use? SCSS   [ https://sass-lang.com/documentation/syntax#scss                ]
CREATE angular-recaptcha-v2/README.md (1064 bytes)
CREATE angular-recaptcha-v2/.editorconfig (274 bytes)
CREATE angular-recaptcha-v2/.gitignore (604 bytes)
CREATE angular-recaptcha-v2/angular.json (3291 bytes)
CREATE angular-recaptcha-v2/package.json (1082 bytes)
CREATE angular-recaptcha-v2/tsconfig.json (783 bytes)
CREATE angular-recaptcha-v2/.browserslistrc (703 bytes)
CREATE angular-recaptcha-v2/karma.conf.js (1437 bytes)
CREATE angular-recaptcha-v2/tsconfig.app.json (287 bytes)
CREATE angular-recaptcha-v2/tsconfig.spec.json (333 bytes)
CREATE angular-recaptcha-v2/src/favicon.ico (948 bytes)
CREATE angular-recaptcha-v2/src/index.html (304 bytes)
CREATE angular-recaptcha-v2/src/main.ts (372 bytes)
CREATE angular-recaptcha-v2/src/polyfills.ts (2820 bytes)
CREATE angular-recaptcha-v2/src/styles.scss (80 bytes)
CREATE angular-recaptcha-v2/src/test.ts (788 bytes)
CREATE angular-recaptcha-v2/src/assets/.gitkeep (0 bytes)
CREATE angular-recaptcha-v2/src/environments/environment.prod.ts (51 bytes)
CREATE angular-recaptcha-v2/src/environments/environment.ts (658 bytes)
CREATE angular-recaptcha-v2/src/app/app-routing.module.ts (245 bytes)
CREATE angular-recaptcha-v2/src/app/app.module.ts (393 bytes)
CREATE angular-recaptcha-v2/src/app/app.component.scss (0 bytes)
CREATE angular-recaptcha-v2/src/app/app.component.html (24617 bytes)
CREATE angular-recaptcha-v2/src/app/app.component.spec.ts (1115 bytes)
CREATE angular-recaptcha-v2/src/app/app.component.ts (225 bytes)
✔ Packages installed successfully.

2. Install and configure the Bootstrap CSS framework. Do steps 2 and 3 of the post Adding the Bootstrap CSS framework to an Angular application.

3. Configure the siteKey variable with the Google reCAPTCHA key in the src/environments/environment.ts and src/environments/environment.prod.ts files as below.

recaptcha: {
  siteKey: '6LfKNi0cAAAAACeYwFRY9_d_qjGhpiwYUo5gNW5-',
},

4. Install the ng-recaptcha library.

npm install ng-recaptcha

5. Import the FormsModule, RecaptchaFormsModule, RecaptchaModule modules. Configure the Google reCAPTCHA key. Change the app.module.ts file and add the lines as below.

import { FormsModule } from '@angular/forms';
import { RECAPTCHA_SETTINGS, RecaptchaFormsModule, RecaptchaModule, RecaptchaSettings } from 'ng-recaptcha';

import { environment } from '../environments/environment';

imports: [
  BrowserModule,
  FormsModule,
  AppRoutingModule,
  RecaptchaModule,
  RecaptchaFormsModule,
],
providers: [
  {
    provide: RECAPTCHA_SETTINGS,
    useValue: {
      siteKey: environment.recaptcha.siteKey,
    } as RecaptchaSettings,
  },
],

6. Remove the contents of the AppComponent class from the src/app/app.component.ts file. Import the NgForm component and create the send method as below.

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

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.scss'],
})
export class AppComponent {

  token: string|undefined;

  constructor() {
    this.token = undefined;
  }

  public send(form: NgForm): void {
    if (form.invalid) {
      for (const control of Object.keys(form.controls)) {
        form.controls[control].markAsTouched();
      }
      return;
    }

    console.debug(`Token [${this.token}] generated`);
  }

}

7. Remove the contents of the src/app/app.component.html file. Add the re-captcha component as below.

<div class="container-fluid py-3">
  <h1>Angular reCAPTCHA v2</h1>

  <form #form="ngForm">
    <div class="row mt-3">
      <div class="col-sm-12 mb-2">
        <re-captcha id="recaptcha" name="recaptcha" #recaptcha="ngModel" [(ngModel)]="token" required [class.is-invalid]="recaptcha.invalid && (recaptcha.dirty || recaptcha.touched)"></re-captcha>
        <div *ngIf="recaptcha.invalid && (recaptcha.dirty || recaptcha.touched)" class="invalid-feedback">
          <div *ngIf="recaptcha.errors?.['required']">This field is required.</div>
        </div>
      </div>
    </div>
    <div class="row">
      <div class="col-sm-12 mb-2">
        <button type="button" class="btn btn-sm btn-primary" (click)="send(form)">Send</button>
      </div>
    </div>
  </form>
</div>

8. Add the style in the src/app/app.component.scss file as below.

re-captcha.is-invalid > div {
  border: 1px solid #dc3545 !important;
  border-radius: 0.2rem;
}

9. Run the application with the command below.

npm start

> angular-recaptcha-v2@0.0.0 start
> ng serve

✔ Browser application bundle generation complete.

Initial Chunk Files | Names         |      Size
vendor.js           | vendor        |   2.73 MB
styles.css          | styles        | 266.58 kB
polyfills.js        | polyfills     | 128.52 kB
scripts.js          | scripts       |  76.67 kB
main.js             | main          |  15.54 kB
runtime.js          | runtime       |   6.64 kB

                    | Initial Total |   3.21 MB

Build at: 2021-08-28T12:35:07.166Z - Hash: 0612b9d911a0acdf2b42 - Time: 10102ms

** Angular Live Development Server is listening on localhost:4200, open your browser on http://localhost:4200/ **


✔ Compiled successfully.

10. Ready! Access the URL http://localhost:4200/ and check if the application is working. See the application working on GitHub Pages and Stackblitz.

The application repository is available at https://github.com/rodrigokamada/angular-recaptcha-v2.

This tutorial was posted on my blog in portuguese.