While using Custom Checkout, you can add custom fields and restrict their input.

var formatter = Razorpay.setFormatter(parentFormElement)

formatter.add('card', cardField)
  .on('change', function() {
    this.value; // contains the latest unformatted value
    this.el; // contains the reference to cardField
    this.prettyValue; // contains formatted value. It might not immediately reflect in DOM
    this.caretPosition; // index at which caret is right now. reflects element.selectionStart
    this.type; // card network. Possible values listed below
    this.maxLen; // maximum permissible length for this type of card
    this.isValid(); // card number validity
  })
  .on('network', function(o) {
    // same params as change event
  })

// restrict format to "MM / YY" format
formatter.add('expiry', expiryField)

// restrict to numbers only. typing characters would not produce anything.
formatter.add('number', numberField)

// this will restrict to numbers, with "+" allowed at first character
formatter.add('contact', contactField)

// unbind events once done
formatter.off()

Change and Network Events

change

Event fired when unformatted value of target input field changes.

network

Event specific to card fields, fired when card type changes.

Possible Values

card network type

visa
mastercard
maestro16 (Maestro cards with 16 digits that also have cvv and expiry)
maestro
rupay
American Express
discover

maxLen

15
16
19

<script src="https://checkout.razorpay.com/v1/razorpay.js"></script>

Example

Check an example code below:

// shortcut function for document.getElementById
var getEl = document.getElementById.bind(document);
var formatter = Razorpay.setFormatter(getEl('parent-form'));
var cvvField = getEl('card_cvv');

formatter.add('card', getEl('card_number'))
  .on('network', function(o) {

    var type = this.type; // e.g. 'visa'

    // set length of cvv element based on mastercard card
    var cvvlen = type === 'amex' ? 4 : 3;
    cvvField.maxLength = cvvlen;
    cvvField.pattern = '^[0-9]{' + cvvlen + '}$';

    getEl('card_type').innerHTML = type;
  })
  .on('change', function() {
    var isValid = this.isValid();
    getEl('card_valid').innerHTML = isValid ? 'valid' : 'invalid';

    // automatically focus next field if card number is valid and filled
    if (isValid && this.el.value.length === this.caretPosition) {
      getEl('card_expiry').focus();
    }
  })

formatter.add('expiry', getEl('card_expiry'))
  .on('change', function() {
    var isValid = this.isValid();
    getEl('expiry_valid').innerHTML = isValid ? 'valid' : 'invalid';

    // automatically focus next field if card number is valid and filled
    if (isValid && this.el.value.length === this.caretPosition) {
      getEl('card_cvv').focus();
    }
  })

Input Restriction in Custom Fields

Change and Network Events

Possible Values

Example