TypeError: functionName is not a function but I've defined it as a function-CodePudding

Here is the error:

        logPunishment(target.id, logObj)
        ^

TypeError: logPunishment is not a function

Code: bot/components/ban.js

const { logPunishment } = require('../db.js')
logPunishment(input1, input2)

some code of: bot/db.js:

async function logPunishment(userId, punishmentObject){
    data = await User.findOne({id: userId})
    if (!data){
        await User.create({id: userId, punishments: []})
        data = await User.findOne({id: userId})   
    }
    punishments = data.punishments
    punishments.push(punishmentObject)
    User.updateOne({id: userId, punishments: punishments})
}


module.exports.logPunishment = logPunishment

logPunishment is clearly a function, but why does it say its not a function? After console.log(logPunishment) this is the result:

undefined

why is that I couldn't understand. Please help! What can I do to fix it now? There are no other errors(for now) apart this Please someone help!!! I have tried this as per a answer

const logPunishment = require('../db.js').logPunishment,

which didn't work Also I'm getting this warning after running the program:

(node:40712) Warning: Accessing non-existent property 'logPunishment' of module exports inside circular dependency

I m not overiding any exports, I have confirmed it.

CodePudding user response：

TL;DR it's because of your circular dependency. Consider the following two files in the same directory:

a.js

const { b } = require('./b');

module.exports.a = 'hello world';

console.log(b());

and b.js

const { a } = require('./a.js');
function b() {
    return a;
}

module.exports.b = b;

If you run node a.js you'll see the circular dependency error

(node:9235) Warning: Accessing non-existent property 'a' of module exports inside circular dependency

If you run node b.js you'll see

TypeError: b is not a function

This has to do with how requires get resolved when there are circular dependencies. If you run a then it requires b which requires a which means b gets a's unfinished exports, so you'll see undefined print instead of hello world. If you run b you'll get b's unfinished exports in a which means that you'll be calling undefined as a function

You can fix it by moving the things that b requires from a into a different file: there's not really a good reason to use circular dependencies.