How to pass a Parameter from URL to Query in UI Page

Retrieve Parameter Value from URL in UI page:
  <g:evaluate var="sysparm_sysid">
            var sysparm_sysid = RP.getParameterValue("sysparm_sysid");
                      sysparm_sysid;
  </g:evaluate>
   Use parameter in your script:
  <g:evaluate var="jvar_user" object="true" jelly="true">
                  var gr = new GlideRecord("incident");
                            gr.get(jelly.sysparm_sysid);
                            gr;
  </g:evaluate>