Open & control browser-application (IE, Firefox, Chrome) on Win7


Hey Guys,
i’m new in electron/node.
My final goal is an app with weblinks inside.
This weblinks contains options for browser selection and logindata.
Actual i’m able to open a website in a selected browser.
The browser focus automatically. Now i want to check if the requested site are loaded.
Two of my ideas for checking if the web-content are full loaded are following:
1: Control the process (i never worked on this systemlevel) and check the state
2: Check the sourcecode for an defined keyword
May someone has an idea how to realise?
Thank you and BR