Just wanted to Share a Script which will help in checking if the Logged in User belongs to a SharePoint user group and based on it disable some controls in editfrm.aspx on Custom List.  It uses JQUERY.

 ExecuteOrDelayUntilScriptLoaded(disableControls, “sp.js”);
function disableControls()
{
clientContext = new SP.ClientContext();
groupCollection = clientContext.get_web().get_siteGroups();
group = groupCollection.getById(21); //The ID of the SharePoint user group
users = group.get_users();
clientContext.load(group);
clientContext.load(users);
currentUser = clientContext.get_web().get_currentUser();
clientContext.load(currentUser);
clientContext.executeQueryAsync(Function.createDelegate(this,
this.onQuerySucceeded), Function.createDelegate(this,
this.onQueryFailed));
RefreshCommandUI();
}
function onQuerySucceeded()
{
if(users.get_count() >0)
{
UserExistInGroup = false;
for(var i=0; i < users.get_count(); i++)
{
if(users.itemAt(i).get_loginName() == this.currentUser.get_loginName())
{
UserExistInGroup = true;
break;
}
}
}
if (UserExistInGroup)
{
var p=$(‘input[title=Priority'); //Name of the columns that needs to be disabled
var i=$('input[title=Range]‘); //Name of the columns that needs to be disabled
$($(p)[0]).attr(‘disabled’,false);
$($(i)[0]).attr(‘disabled’,false);
}
else
{
var p=$(‘input[title=Priority');
var i=$('input[title=Range');
$($(p)[0]).attr(‘disabled’,true);
$($(i)[0]).attr(‘disabled’,true);
}
}
function onQueryFailed(sender, args)
{
var p=$(‘input[title=Priority');
var i=$('input[title=Range]‘);
$($(p)[0]).attr(‘disabled’,true);
$($(i)[0]).attr(‘disabled’,true);
}