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Afzal Imam
Afzal Imam

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Create Custom Captcha in HTML CSS & JavaScript

Hey friends, today in this blog, you’ll learn how to create Custom Captcha in HTML CSS & JavaScript. In the earlier blog, I have shared how to Detect User Browser using JavaScript, and it’s time to create a simple captcha program.

Mostly, Captcha is used on the comment or contact form of the websites to restrict robots (bot) from commenting on a blog post or sending a message to the admin. There can be random images or codes in the captcha, and the users must have to select correct images or match the codes to complete their task.

In this small project [Custom Captcha in JavaScript], there is an image with the random 6 characters and numbers. You can also refresh the captcha code and get a new one using the reload button.

In the input field, you have to enter the captcha codes that are shown on the image. If your codes matched with the captcha codes, then there is appears a success message else there appears an error message. If you’ve matched the codes, then after 4 seconds there will be generated a new one captcha code.

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I hope you liked this simple captcha program and want to get source codes but don’t worry I have given codes and source code files at the bottom of this page from where you can copy-paste codes the source code files.

But before copying codes, let’s understand the basic codes and concepts of this program. At first, in the JavaScript file, I have stored all characters and numbers in the array, then inside for loop, using Math.random() function I got 6 random characters from the given array.

And passed these codes or characters in the captcha by adding space between each character. After this, I got user-entered values, split them, and joined them with space (‘ ‘) so users don’t need to enter spaces to match the codes.

Once I joined the user values then I matched this user value with the captcha codes. If the value is not matched I’ve shown an error message, and if the value is matched I’ve shown a success message and generate the new random codes after 4 seconds using the setTimeout() function.

Create Custom Captcha in JavaScript [Source Codes]

To create this program [Custom Captcha in JavaScript]. First, you need to create three Files: HTML, CSS & JavaScript File. After creating these files just paste the following codes into your file.

First, create an HTML file with the name of index.html and paste the given codes into your HTML file. You’ve to create a file with .html extension and remember the image that is used on this program will not appear.

<!DOCTYPE html>
<!-- Coding By CodingNepal - youtube.com/codingnepal -->
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Custom Captcha in JavaScript | CodingNepal</title>
  <link rel="stylesheet" href="style.css">
  <!-- Font Awesome CDN Link for Icons -->
  <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.15.3/css/all.min.css"/>
</head>
<body>
  <div class="wrapper">
    <header>Captcha in JavaScript</header>
    <div class="captcha-area">
      <div class="captcha-img">
        <img src="captcha-bg.png" alt="Captch Background">
        <span class="captcha"></span>
      </div>
      <button class="reload-btn"><i class="fas fa-redo-alt"></i></button>
    </div>
    <form action="#" class="input-area">
      <input type="text" placeholder="Enter captcha" maxlength="6" spellcheck="false" required>
      <button class="check-btn">Check</button>
    </form>
    <div class="status-text"></div>
  </div>
  <script src="script.js"></script>
</body>
</html>
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Last, create a JavaScript file with the name of script.js and paste the given codes in your JavaScript file. Remember, you’ve to create a file with .js extension.

const captcha = document.querySelector(".captcha"),
reloadBtn = document.querySelector(".reload-btn"),
inputField = document.querySelector(".input-area input"),
checkBtn = document.querySelector(".check-btn"),
statusTxt = document.querySelector(".status-text");

//storing all captcha characters in array
let allCharacters = ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O',
                     'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd',
                     'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
                     't', 'u', 'v', 'w', 'x', 'y', 'z', 0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
function getCaptcha(){
  for (let i = 0; i < 6; i++) { //getting 6 random characters from the array
    let randomCharacter = allCharacters[Math.floor(Math.random() * allCharacters.length)];
    captcha.innerText += ` ${randomCharacter}`; //passing 6 random characters inside captcha innerText
  }
}
getCaptcha(); //calling getCaptcha when the page open
//calling getCaptcha & removeContent on the reload btn click
reloadBtn.addEventListener("click", ()=>{
  removeContent();
  getCaptcha();
});

checkBtn.addEventListener("click", e =>{
  e.preventDefault(); //preventing button from it's default behaviour
  statusTxt.style.display = "block";
  //adding space after each character of user entered values because I've added spaces while generating captcha
  let inputVal = inputField.value.split('').join(' ');
  if(inputVal == captcha.innerText){ //if captcha matched
    statusTxt.style.color = "#4db2ec";
    statusTxt.innerText = "Nice! You don't appear to be a robot.";
    setTimeout(()=>{ //calling removeContent & getCaptcha after 2 seconds
      removeContent();
      getCaptcha();
    }, 2000);
  }else{
    statusTxt.style.color = "#ff0000";
    statusTxt.innerText = "Captcha not matched. Please try again!";
  }
});

function removeContent(){
 inputField.value = "";
 captcha.innerText = "";
 statusTxt.style.display = "none";
}
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That’s all, now you’ve successfully created a Custom Captcha in HTML CSS & JavaScript. So this is all for today.
Thanks!

Also Read
6 Key Lesson’s to Learn From Rich Dad Poor Dad for Programmers.

For more details please visit Code With Imam.

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