Notes

I am using Node version v12.14.1. This also worked in v10.

Purpose

This demonstrates how to use the new import() in Node.js in different ways to dynamically import modules from the filesystem.

The expected results when dynamically importing in a loop would result in all of your specified modules being loaded; i.e.) in this example, modules alpha and beta should be loaded.

Use Cases

When I started one of my projects, I used babel on the backend so that I could use implement import / export. As a result, I am using import() in a Node.js backend, as opposed to a front-end where it is most commonly seen. You may find it way cleaner to simply use require() to import things dynamically. I took the liberty of showing the different ways I've discovered to import modules dynamically.

The reason I wanted to start loading modules dynamically is because of a graphql project I startred. You'll commonly hear that the typeDefs are in one large file (which is apparently what facebook does).

This can be undesirable for some if you like to keep your project organized in a "relative" structure. That is, if you wanted to keep all files relevant to each model in a corresponding /Models directory, which would require you to find a way to break up the graphql schema. If you are using .graphql files (plain text) instead of graphql-tag or graphql-tools to build your schema in template strings, then you would then have to either:

1. Import each .graphql schema statically and join them into one string before passing it to the graphql server prior to initialization
2. Import each .graphql schema dynampically, and join them the same way

You can do this statically, but that can be a pain if you have many models, which is why I decided to look into using the dynamic import() feature and require(), the former of which is the easiest, cleanest way to do it.

References:

• https://nodejs.org/api/esm.html
• https://javascript.info/modules-dynamic-imports

How to Run:

yarn run start

Expected Output

arn run v1.19.1
$ babel-node index.js
require example 1: WORKS AS EXPECTED
 [
  { default: { name: 'alpha module' } },
  { default: { name: 'beta module' } }
]
ex 1 WORKS AS EXPECTED [
  { default: { name: 'alpha module' } },
  { default: { name: 'beta module' } }
]
ex 2 WORKS AS EXPECTED [
  { default: { name: 'alpha module' } },
  { default: { name: 'beta module' } }
]
ex 3 DOES NOT WORK AS EXPECTED (returns the same module in all resulting    promises!) [
  { default: { name: 'beta module' } },
  { default: { name: 'beta module' } }
]
ex 4 WORKS AS EXPECTED [
  { default: { name: 'alpha module' } },
  { default: { name: 'beta module' } }
]
promise example 1: DOES NOT WORK AS EXPECTED (returns the same module in    all resulting promises!)
 [ { name: 'beta module' }, { name: 'beta module' } ]
promise example 2: WORKS AS EXPECTED (but at the cost of specifying extra    data in the import().then() resolver)
 [ { name: 'alpha module' }, { name: 'beta module' } ]
promise example 3: WORKS AS EXPECTED
 [ { name: 'alpha module' }, { name: 'beta module' } ]
Done in 1.56s.