文件夹作为模块内的文件夹作为模块NodeJS

Question

I am having trouble requiring from parent directories within NodeJS. I have read this post, but still couldn't figure it out.

node.js require from parent folder

This is my file structure:

-- components/
    -- windows/
        -- index.js
    -- index.js
-- main.js

This is the code:

// /main.js
var components = require("./components")
components.windows.inner()

// /components/index.js
module.exports = {
    windows: require("./windows"),
    foo: "foo",
}

// /components/windows/index.js
var components = require("./..")
module.exports.inner = function() {
    console.log(components.foo)
}

When I run main.js , the inner() function prints undefined .

Why is it printing undefined? Shouldn't it print foo? Am I missing something about how Node works?

Answer 1

You just built up a "circular dependency". /components/windows/ requires /components/ , which requires /components/windows/ , which requires ...

To resolve those nevertheless, NodeJS initializes the exports to an empty object and rewrites them to the exports object after the module initialized. Therefore you can access /components/windows from inside /components/ but not the other way round.

To remove the circular dependency, move foo to another file that you require in both modules.