faultcode:'sf:INSUFFICIENT_ACCESS', faultstring:'ClassName: no access allowed to this class.', Salesforce
Are you getting the above error in salesforce while the javascript is getting executed ?
the reson is the user doesnt have sufficient access to the Apex class.
Do the following and the issue will get resolved.
Go to Setup->Develop->Apex Classses-> open the Class -> Click Security Button -> Add access to the profile from which you are trying to perform the action.