On NW.js, you could write/read this information to another file yourself, using the NodeWebkit's functionalities:
Write a text file to the user's local system. If the file does not exist, it is created. If the file already exists, its content is overwritten.
Open the given file and return its text content as a string. Note that each time this expression is used the file is opened and read from disk. Therefore if the expression is used twice, the file is opened and read twice, which can impact performance. If necessary first read the file to a variable, then reference the variable multiple times.
Alternatively, I believe you could also write/read such data using LocalStorage:
For the system time, you may need to use this: