Angular 2 component for Google reCAPTCHA

ng2-recaptcha

A simple, configurable, easy-to-start component for handling reCAPTCHA.

Installation

The easiest way is to install trough npm:

npm i ng2-recaptcha --save

In order to take advantage of type-checking system you should also install grecaptcha typings:

typings install dt~grecaptcha --save --global

Or, if you're using TypeScript 2 or angular-cli:

npm install @types/grecaptcha --save-dev

Usage (see in action)

To start with, you need to add one of the Recaptcha modules (more on that later):

import { RecaptchaModule } from 'ng2-recaptcha';
import { BrowserModule }  from '@angular/platform-browser';

@NgModule({
  bootstrap: [MyApp],
  declarations: [MyApp],
  imports: [
    BrowserModule,
    RecaptchaModule.forRoot(), // Keep in mind the "forRoot"-magic nuances!
  ],
})
export class MyAppModule { }

Once you have done that, the rest is simple:

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { Component } from '@angular/core';

@Component({
    selector: 'my-app',
    template: `<recaptcha (resolved)="resolved($event)" siteKey="YOUR_SITE_KEY"></recaptcha>`,
}) export class MyApp {
    resolved(captchaResponse: string) {
        console.log(`Resolved captcha with response ${captchaResponse}:`);
    }
}

platformBrowserDynamic().bootstrapModule(MyAppModule);

Modules: "Forms"-ready and "No-forms"

There are two modules available for you:

import { RecaptchaModule } from 'ng2-recaptcha';
import { RecaptchaNoFormsModule } from 'ng2-recaptcha/ng2-recaptcha.noforms';

The difference between them consists in dependencies - RecaptchaModule depends on @angular/forms, while RecaptchaNoFormsModule does not. If you do not rely on Angular 2 forms in your project, you should use the "no-forms" module version, as it does not require the @angular/forms package to be bundled with your code.

Options

The component supports this options:

• siteKey
• theme
• type
• size
• tabIndex

They are all pretty well described in the reCAPTCHA docs, so I won't duplicate it here.

Events

• resolved(response: string). Occurs when the captcha resolution value changed. When user resolves captcha, use response parameter to send to the server for verification. This parameter is equivalent to calling grecaptcha.getResponse.

  If the captcha has expired prior to submitting its value to the server, the component will reset the captcha, and trigger the resolved event with response === null.

Methods

• reset. Performs a manual captcha reset. This method might be useful if your form validation failed, and you need the user to re-enter the captcha.

Specifying a different language (see in action)

<recaptcha> supports various languages. But this settings is global, and cannot be set on a per-captcha basis. This can be overridden by providing your own instance of RecaptchaLoaderService for a particular module:

import { RecaptchaLoaderService } from 'ng2-recaptcha';

@NgModule({
  providers: [
    {
      provide: RecaptchaLoaderService,
      useValue: new RecaptchaLoaderService("fr"), // use French language
    },
  ],
}) export class MyModule { }

You can find the list of supported languages in reCAPTCHA docs.

Loading the reCAPTCHA API by yourself (see in action)

By default, the component assumes that the reCAPTCHA API loading will be handled by the RecaptchaLoaderService. However, you can override that by providing your instance of this service to the Angular DI.

The below code snippet is an example of how such a provider can be implemented.

TL;DR: there should be an Observable that eventually resolves to a grecaptcha-compatible object (e.g. grecaptcha itself).

<script src="https://www.google.com/recaptcha/api.js?render=explicit&amp;onload=onloadCallback"></script>

<script>
    // bootstrap the application once the reCAPTCHA api has loaded
    function onloadCallback() {
        System.import('app').catch(function(err) { console.error(err); });
    }
</script>

import { RecaptchaLoaderService } from 'ng2-recaptcha';

@Injectable()
export class PreloadedRecaptchaAPIService {
  public ready: Observable<ReCaptchaV2.ReCaptcha>;

  constructor() {
    let readySubject = new BehaviorSubject<ReCaptchaV2.ReCaptcha>(grecaptcha);
    this.ready = readySubject.asObservable();
  }
}

@NgModule({
  providers: [
    {
      provide: RecaptchaLoaderService,
      useValue: new PreloadedRecaptchaAPIService(),
    },
  ],
}) export class MyModule { }

Usage with required in forms (see in action)

It's very easy to put recaptcha in an Angular2 form and have it required - just add the required attribute to the <recaptcha> element

@Component({
  selector: 'my-form',
  template: `
  <form>
    <recaptcha
      [(ngModel)]="formModel.captcha"
      name="captcha"
      required
      siteKey="YOUR_SITE_KEY"
    ></recaptcha>
  </form>`,
}) export class MyForm {
  formModel = new MyFormModel();
}