Embodiments relate to determining page loading of user interfaces of web applications. An aspect includes loading a web page at a browser of a client, the web page comprising a plurality of scripting codes. Another aspect includes providing a wrapper function for an existing function in the browser. Another aspect includes determining one or more scripting codes that waiting to run in the web page, and incrementing a counter value for each of the one or more scripting codes that waiting to run in the web page. Another aspect includes determining one or more scripting codes that have that have started execution or completed execution, and decrementing the counter value for each of the one or more scripting codes that complete execution or started execution. Another aspect includes based on determining that the counter value returns to a zero count, determining that the web page is loaded in the browser.