Answer 1

Read the file first

Then JSON.parse

Then length property.

https://code.sololearn.com/ce6O0aTOxQi3/?ref=app

Answer 2

no, your json shouldn't be of 0 bytes. If it is empty, it should be a string of two character {}

Answer 3

kinda strage system you have there.
you can use fs.stat() or fs.statSync() and get .size from the result

but instead of creating empty file for new person, its better to not create the file until you need to actually write to it.
you can use fs.exist or fs.access to check if file is exist

Answer 4

empty like its only 0kb file, or empty json object like {} ?