javascript - How to validate a credit card number

Question

I just want to validate a credit card number in the JavaScript code. I have used a regular expression for digit numbers, but I don't know why it is not working!

Here is my function as per below:

function validate_creditcardnumber()
{
    var re16digit = /^d{16}$/
    if (document.myform.CreditCardNumber.value.search(re16digit) == -1)
        alert("Please enter your 16 digit credit card numbers");
    return false;
}

Answer 1

I hope the following two links help to solve your problem.

FYI, various credit cards are available in the world. So, your thought is wrong. Credit cards have some format. See the following links. The first one is pure JavaScript and the second one is using jQuery.

• JavaScript Credit Card Validation Function

• jQuery-Validation-Extension

Demo:

function testCreditCard() {
  myCardNo = document.getElementById('CardNumber').value;
  myCardType = document.getElementById('CardType').value;
  if (checkCreditCard(myCardNo, myCardType)) {
    alert("Credit card has a valid format")
  } else {
    alert(ccErrors[ccErrorNo])
  };
}

<script src="https://www.braemoor.co.uk/software/_private/creditcard.js"></script>

<!-- COPIED THE DEMO CODE FROM THE SOURCE WEBSITE (https://www.braemoor.co.uk/software/creditcard.shtml) -->

<table>
  <tbody>
    <tr>
      <td style="padding-right: 30px;">American Express</td>
      <td>3400 0000 0000 009</td>
    </tr>
    <tr>
      <td>Carte Blanche</td>
      <td>3000 0000 0000 04</td>
    </tr>
    <tr>
      <td>Discover</td>
      <td>6011 0000 0000 0004</td>
    </tr>
    <tr>
      <td>Diners Club</td>
      <td>3852 0000 0232 37</td>
    </tr>
    <tr>
      <td>enRoute</td>
      <td>2014 0000 0000 009</td>
    </tr>
    <tr>
      <td>JCB</td>
      <td>3530 111333300000</td>
    </tr>
    <tr>
      <td>MasterCard</td>
      <td>5500 0000 0000 0004</td>
    </tr>
    <tr>
      <td>Solo</td>
      <td>6334 0000 0000 0004</td>
    </tr>
    <tr>
      <td>Switch</td>
      <td>4903 0100 0000 0009</td>
    </tr>
    <tr>
      <td>Visa</td>
      <td>4111 1111 1111 1111</td>
    </tr>
    <tr>
      <td>Laser</td>
      <td>6304 1000 0000 0008</td>
    </tr>
  </tbody>
</table>
<hr /> Card Number:
<select tabindex="11" id="CardType" style="margin-left: 10px;">
  <option value="AmEx">American Express</option>
  <option value="CarteBlanche">Carte Blanche</option>
  <option value="DinersClub">Diners Club</option>
  <option value="Discover">Discover</option>
  <option value="EnRoute">enRoute</option>
  <option value="JCB">JCB</option>
  <option value="Maestro">Maestro</option>
  <option value="MasterCard">MasterCard</option>
  <option value="Solo">Solo</option>
  <option value="Switch">Switch</option>
  <option value="Visa">Visa</option>
  <option value="VisaElectron">Visa Electron</option>
  <option value="LaserCard">Laser</option>
</select> <input type="text" id="CardNumber" maxlength="24" size="24" style="margin-left: 10px;"> <button id="mybutton" type="button" onclick="testCreditCard();" style="margin-left: 10px; color: #f00;">Check</button>

<p style="color: red; font-size: 10px;"> COPIED THE DEMO CODE FROM TEH SOURCE WEBSITE (https://www.braemoor.co.uk/software/creditcard.shtml) </p>