How can I tell in JavaScript what path separator is used in the OS where the script is running?
As already answered here, you can find the OS specific path separator with path.join to manually construct your path. But you can also let path.join do the job, which is my preferred solution when dealing with path constructions:
Example:
const path = require('path');
const directory = 'logs';
const file = 'data.json';
const path1 = `${directory}${path.sep}${file}`;
const path2 = path.join(directory, file);
console.log(path1); // Shows "logs\data.json" on Windows
console.log(path2); // Also shows "logs\data.json" on Windows