Creating a CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) in Angular 9 involves several steps. In this example, we'll demonstrate how to implement a simple CAPTCHA using Angular 9 and TypeScript. The CAPTCHA will consist of a random mathematical expression that the user needs to solve to prove they are human.
```bash
ng new captcha-app
cd captcha-app
```
```bash
ng generate component captcha
```
```typescript
import { Component, OnInit } from '@angular/core';
@Component({
})
export class CaptchaComponent implements OnInit {
ngOnInit() {
this.generateCaptcha();
}
generateCaptcha() {
this.captchaExpression = `${operand1} ${operator} ${operand2}`;
}
checkCaptcha() {
// Evaluate the expression to get the expected result
const expectedAnswer = eval(this.captchaExpression);
// Check if the user's answer matches the expected result
this.isCaptchaValid = this.userAnswer === expectedAnswer;
// Generate a new CAPTCHA after each attempt (optional)
this.generateCaptcha();
this.userAnswer = null;
}
}
```
```html
Solve the following CAPTCHA:
{{ captchaExpression }} =
CAPTCHA successfully solved!
```
```css
div {
}
input {
}
button {
}
```
```typescript
import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppComponent } from './app.component';
import { CaptchaComponent } from './captcha/captcha.component';
@NgModule({
})
export class AppModule {}
```
```html
```
```bash
ng serve
```
Now, when you access your Angular app in the browser, you'll see a simple CAPTCHA with a randomly generated mathematical expression. Users need to solve the expression correctly to prove they are human. If they get it right, a success message will be displayed, and a new CAPTCHA will be generated for the next attempt.
Please note that this example is a basic implementation of CAPTCHA for demonstration purposes. In a real-world scenario, you would want to enhance the CAPTCHA's complexity and security to make it more robust against automated attacks.