jQuery – Make multiple field Required with warning at WP Admin backend

I fixed the issues by replacing default HTML warning message using function setCustomValidity(). The default HTML warning message is issued at invalid field so that users know where to correct:

      // HTML:
      <input type="text" name="post_title" size="30" value="" id="title">
      <input type="text" name="price" size="30" value="" id="price">

      // jQuery:
      // Make post title field required - when it is blank, a default warning is issued
      jQuery('#title').prop('required', true);    
      
      // Change default HTML warning message when title field is blank
      let title = document.getElementById("title");
      title.addEventListener("input", function(e){
        title.setCustomValidity('');
      });
      title.addEventListener("invalid", function(e){
        title.setCustomValidity('Please enter your post title'); //custom validation message for invalid text
      });
      
      // Make price field required - when it is blank, a default warning is issued
      jQuery('#price').prop('required', true);    
      
      // Change default HTML warning message when price field is blank
      let price = document.getElementById("price");
      price.addEventListener("input", function(e){
        price.setCustomValidity('');
      });
      price.addEventListener("invalid", function(e){
        price.setCustomValidity('Please enter a price'); //custom validation message for invalid text
      });

Many thanks