Extend Item to read custom Barcode

Hi All,
Maybe not the best title but my problem is related to Quotation reading my Barcode (2800123017965)
This Barcode is composed by Serial Number (0123) + Kg (1.796)
I have managed to do this on POS where it does the get_item and has the INPUT…

Which event i need to capture before the rest of the code says Item does not exist create?

Thought of $.extend but what function should be?


Any ideas to achieve this?