@master.oren
You are misunderstanding how mobione HTML5 apps work. They are based on classic ajax model. Only 1 document is loaded (DOM). All screens are either statically merged into a single document or are merged into the DOM at runtime (remote UI screen). Thus, documentReadyHandler() is called only once when the main html file is loaded. This function can be found in the folder <mainscreen>-www/<mainscreen>_custom.js – replace <mainscreen> with the name of your startup .mobi file.
If your screens are linked to the <mainscreen>.mobi via GotoScreen actions then all of the linked .mobi files will automatically be generated to html. Do not manually include an <secondaryscreen>_custom.js in your project since this may override the default callbacks to key app events, e.g., pre/post screen transition, post orientation change, documentReadyHandler ….
I typically delete the www folders of intermediate screens that I test individually.
I hope this make sense.