can i store .js file in local memory of my system and give that .js file path in html code while creating product?
yes, you can give your local memory path.
I hope this will be helpfull.
Yes, you can.
Put the script tag in the HTML head with src attribute to the JS file location.
Yes, You can do it.
It would be better if You use a text editor like sublime or VScodes and save both the HTML and JS file in the same directory(folder).
By this u can save time by adding relative path instead of actual file path of JS file.