How to know what kind of permission (Full, manage, write) is used for the current App?

I planing to build an JavaScript library to manipulate SharePoint Lists and Items , which developer can use with there SharePoint Hosted apps, and I want to publish on CodePlex,

anyway, this JS library can access the items using two ways, and both of them are working fine, but one of them have better performance.

form my library I need to know what kind of permission (Full, manage, write) is used for the current App, and based on that I can run the fit code.

Update: My App authorization policy is default (App-only policy)