JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="///ajax.googleapis.com/ajax/libs/jqueryui/1.8.18/themes/base/jquery-ui.css">
<input id ="myID" type="checkbox">

JavaScript

$('#myID').click(function() {
  var isChecked = this.checked; // this.checked is enough or $(this).is(':checked')
  if(isChecked)
    {
        alert('checked');
        //$('#myField').replaceWith('Something');
    }
    else
    {
        alert('unchecked');
        //$('#myField').replaceWith('Something Else');
    }

});