The QlikView API guide shows the supported functions in QlikView Visual Basic script (VBScript) based macros.
QlikView 11 API Guide; http://community.qlikview.com/docs/DOC-2640
QlikView 10 API Guide; http://community.qlikview.com/docs/DOC-2415
QlikView 12.00 API Guide; http://help.qlik.com/en-US/qlikview-developer/12.0/Subsystems/Automation/Content/automation-introduction.htm
QlikView 12.10 API Guide; http://help.qlik.com/en-US/qlikview-developer/12.1/Subsystems/Automation/Content/automation-introduction.htm
In general it is recommended to avoid using VBScript for automation, and instead utilize QlikView's triggered actions to accomplish automation.
Please consider that in QlikView applications accessed by the full browser (AJAX) client macros will be executed on server side, as the client side can not execute VBScript. This means that the majority of VBScript command can not be executed when using the full browser version client. For this reason make sure to test the QlikView application in the intended environment during development, so that works as expected when deployed in production.
Notice that using macros in a QlikView Server is limited as described int he QlikView reference manual's section "Using Macros in QV Documents on the QV-Server".