Getting ""gReqInfo is not defined"" error for Image Onload on mobile

I am attempting to follow the instructions to use the Image Onload technique on mobile pages (https://community.quickbase.com/quickbase/topics/how-to-get-iol-working-on-mobile), and am using device emulation (iPhone X) in the Chrome DevTools to test. When I navigate to a page and attempt to activate the JS by clicking the IOL element (I have it set up for onclick, not onload), nothing happens. If I reload the page, I get the following error in console: Uncaught ReferenceError: gReqInfo is not defined. However, if I type gReqInfo into the console, I get the expected output with no error. Can anyone help me with this?