Node JS中的Require模块

Question

I used Node JS for web application development. I have a confusion in require() module. I am requiring a JS file located in file_handler directory. What is the difference between both of the following?

// in server.js

var chat = require("./file_handler/chat.js");    // Does not work

OR

var chat = require("./file_handler/chat.js")(); // It works

Why is the extra parenthesis in the last of the statement?

Answer 1

In the first line the exported function is assigned to chat variable so then you can call it like next like chat();

In the second one the return of exported function is returned to chat variable.

Answer 2

It is actually based on what you export in your module. If you export the object you need, you can just directly do require('module') . If you export a function which returns the object you need, you have to execute that exported function require('module')() to get the desired object.

Read the documentation https://nodejs.org/api/modules.html