How to write a script to restrict Ninja Form date picker for past dates?

Solution:

It appears Ninja Forms has an advance date picker option I am not familiar with it but here is the link

NOW I don’t know the exact Ninja Forms syntax but this should jolt your brain to get started. Other wise you can create a small custom WP-plugin using a add_filter() and function like

<?php
  
  add_filter( 'ninja_form_date_limt'  );
  
  function ninja_form_date_limt() {
      wp_enqueue_script( 
        'ninja_form_date_limt', 
        plugin_dir_url( __FILE__ ) . 'script.js', 
        array( 'jquery' ), 
        false, 
        true 
      );
  }

This calls on a JQuery or JavaScript function in your theme/js/script.js file or wherever you keep custom JS Which could will could use something like this.

var tomorrow = new Date();
tomorrow.setDate(tomorrow.getDate() + 1);
dateObject.pikaday.setMinDate(tomorrow);