Locally creating and saving files on HTML site

I was working on a simple reminder and note taking page using HTML and JS and one of the things I need was to be able to permanently save the reminders and more files.

I decided I could use JSON file to hold the reminder data as an object and store it in an array, the same thing to the name of the txt files for the notes The problem I ran into was that I can't creat or modify any file through the client side.

So, I wanted to knw if there is any way I could

1. Use NodeJS or any alternative that would let me create or modify files in the same folder.
2. Make it portable.

Thank you.