How to Create a CAPTCHA Generator Using HTML, CSS, and JavaScript

CAPTCHA is an anti-bot security feature that combines distorted letters and numbers. It is employed to differentiate between humans and automated bots. Its purpose is to restrict access to specific online features like registration or comment posting. The distorted characters pose a challenge that bots have difficulty solving.

Creating a captcha generator using HTML, CSS, and JavaScript could be quite an important skill for a developer. Whether you’re building a personal website or developing a client’s site, being able to create your own captchas will give you more control over the security of your site.

source : cloudflare

In this tutorial, we will show you how to create a simple captcha generator using HTML, CSS, and JavaScript. We will start by creating a basic HTML form. Then, we will use CSS to style the form and make it look more attractive. Finally, we will use JavaScript to generate a random CAPTCHA code and display it on the form.

Step 1: Create a Basic HTML Form

The first step is to create a basic HTML form. This form will be used to collect the user's input for the CAPTCHA code. The following code shows the basic HTML structure for a CAPTCHA form:

HTML

<form action="/" method="post">

  <input type="text" name="captcha" />

  <input type="submit" value="Submit" />

</form>

Step 2: Style the Form with CSS

Now that we have created the basic HTML form, we can use CSS to style it and make it look more attractive. The following code shows the CSS that we will use to style the form:

CSS

form {

  width: 300px;

  margin: 0 auto;

  padding: 10px;

  border: 1px solid #ccc;

}

input {

  width: 200px;

  padding: 10px;

  border: 1px solid #ccc;

}

button {

  background-color: #000;

  color: #fff;

  padding: 10px;

  border: none;

  cursor: pointer;

}

Step 3: Generate a Random CAPTCHA Code with JavaScript

Now that we have styled the form, we can use JavaScript to generate a random CAPTCHA code and display it on the form. The following code shows how to generate a random CAPTCHA code:

JavaScript

function generateCaptchaCode() {

  var letters = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";

  var code = "";

  for (var i = 0; i < 6; i++) {

    code += letters.charAt(Math.floor(Math.random() * letters.length));

  }

  document.getElementById("captcha").value = code;

}

The above code will check if the CAPTCHA code that the user enters is empty or if it does not match the code that was generated. If the code is invalid, an alert will be displayed and the form will not be submitted.

Conclusion

In this tutorial, we have shown you how to create a simple CAPTCHA generator using HTML, CSS, and JavaScript. We hope that this tutorial has been helpful.