JSFiddle - React, Tailwind, and code Playground

by slawe

HTML

<input type="text" class="customer_fields_input_label">
<input type="text" class="customer_fields_input_key_name" disabled>

JavaScript

$(function () {
  var label = $('.customer_fields_input_label'),
      key_name = $('.customer_fields_input_key_name');

  label.on('input', function() {
  	var result = $(this).val().toLowerCase().replaceAll(" ", "_");
  	console.log(result);
    key_name.val(result);
});

});