I was following the instruction from msdn to get WorkflowSubscriptionService over JSOM.
Working with the SharePoint 2013 Workflow Services Client Side Object Model: http://msdn.microsoft.com/en-us/library/office/dn481315(v=office.15).aspx
var clientContext = SP.ClientContext.get_current();
var workflowServicesManager = SP.WorkflowServices.WorkflowServicesManager.newObject(clientContext, clientContext.get_web());
var workflowSubscriptionService = workflowServicesManager.getWorkflowSubscriptionService();
These three lines always throw a error: TypeError: Object [object Object] has no method 'get_context' message: "Object [object Object] has no method 'get_context'" stack: (...) get stack: function () { [native code] } set stack: function () { [native code] } proto: Error
I can't find a mistake. Is this a known bug?