What is _spPageContextInfo SharePoint JavaScript Object Model?
In JavaScript Object Model _spPageContextInfo is a main object use to key values like user name, siteurl, userid,etc.
- _spPageContextInfo.webabsoluteurl - Absolute URL of the current Web
- _spPageContextInfo.userid - User Id of login user
- _spPageContextInfo.userloginname - user name of login user
You can learn more about the _spPageContextInfo for followings blog codesharepoint.com
In some occasions "_spPageContextInfo is not defined" error occurs in above error explain in above also
