If you don't want the values to appear in the querystring, then you need to make a POST request:
var form = document.createElement("form");
form.setAttribute("method", "POST");
form.setAttribute("action", "/PostWork/Create");
var contractors = document.createElement("input");
contractors.setAttribute("type", "hidden");
contractors.setAttribute("name", "Contractors");
contractors.setAttribute("value", str);
form.appendChild(contractors);
document.body.appendChild(form);
form.submit();
Your action will obviously need to accept POST requests as well as GET requests. If you haven't added an
[HttpGet]
attribute to the action, it
should just work.