Current version supports tracking sessions only. We measure session by tracking user activity in web application per browser. Session is closed if user is not active for 30 minutes or he closes all browser tabs with application.
npm install appinsights-usage -save
Include following lines to index.js:
var AppInsightsUsage = ;AppInsightsUsage;
See How to get instrumentation key for Applicaton Insights for more details.
To see this metric in Azure portal you need to navigate to Application Insights resource, select Metrics Explorer from the top menu and configure one of the empty charts to display Custom metrics "Session Duration (seconds)" . It can take up to 10 minutes for new custom metric to appear in Azure Portal.