I know how module loading is supposed to work in node.js, but I'm not observing the correct behavior (and it actually seems there is a slight discrepancy if you look in the comments on this answer)
Using nodejs 8.2.1, I have the following structure:
app
|
+ server.js
+ log
| |
| + index.js
+ db
|
+ index.js
In server.js, I call require('./log'), and in /log/index.js, I require('winston') and configure it like so:
let logger = new (winston.Logger)({
transports: [
new (winston.transports.Console)({
name: 'console',
level: logLevel,
handleExceptions: true,
json: false,
colorize: process.env.NODE_ENV === 'dev',
timestamp: true
})
]
});
According to this answer, I should be able to just require('winston') from any other module, and I would get that same configured instance. What I'm actually seeing is, when I require('winston') in db/index.js, a default winston instance is in memory, with no configuration at all. I've stepped through the require.cache as well; no other modules are added to the cache, so as far as I can tell, the same configured instance should be returned, if the cache is working properly. I've verified that the code in log/index.js is being called before the module in db/index.js is being loaded as well.
Any ideas? Should I just be requireing my ./log module in all my dependent modules?
Any ideas? Should I just be requireing my ./log module in all my dependent modules?
Yes you should. Like you said, when you require a module already required by a parent module, you are accessing to the same object. But actually with winston you are importing a constructor (in fact, to configure it, you define a variable called logger and you create a NEW winson logger).
You should only export logger from logs/index.js (and use const instead of let)
const logger = new (winston.Logger)({ ... })
module.exports = logger
in another module you could do
const logger = require('./log/index.js') // './log' is the same
logger will always be the same object :)