Contact Form 7 prevent duplicate submissions

script.js

// Once the form is submitted, disable the button
$(document).on( 'submit', '.wpcf7-form', function() {
  var $submit =  $(this).find('[type=submit]');

  // Disable the button
  $submit.attr('disabled', true)
    // Create a backup of the button text
    .data( 'original-text', $submit.text() )
    // Change the button text to indicate sending
    .text( 'Sending…' );
});

// After submit, re-enable the button
$(document).on( 'wpcf7submit', '.wpcf7', function (e) {
  var $submit =  $(this).find('[type=submit]');

  // Enable the button again
  $submit.removeAttr('disabled');

  // Reset the button text
  if( $submit.data( 'original-text' ) ) {
    $submit.text( $submit.data( 'original-text' ) );
  }
});