Help me please

ok so i think i figured out part of the problem

local storage can store datafrom page to page IF BOTH PAGES ARE SAME DOMAIN?

if above statement is true that explains why i continually receive “null”

so allow me to further illiterate my illiteracy here by asking …
if i have a page which was made by someone else and i want to transfer data from and to backendless database example page backendless has logged in user data i need to get the logged in users data field "score "
then use it in another page (game) and use the score value as a const or var of the game page (which was not made on my backendless app)
IF THIS MAKES SENSE TO YOU PLEASE HELP ME i need to store and retrieve this data when i enter game then upon exit take updated score and update the users score on backendless database