Node 10 experimental flag for importing/exporting ES6 modules in Node
Even if I jump ship and start using the experimental flag for new projects that I am creating, using ES6 modules in node is still not that easy. As soon as you reference an npm package, you will get an error saying that the code being referenced is not in the Michael Jackson script format aka their file extensions are not ending with “.mjs”. Now I cannot control the npm registry. So this experimental flag usage was not something that I could have used in any project since a node project without npm packages is pretty much useless these days. And I will never work on getting the interoperability among these two correct since there are better ways out there.
Update 11/21/2019: Node 13.2.0 ships support for ECMASCRIPT modules and you no longer require the experimental flag, even though the implementation is still experimental and subject to change. You can read this post to know more about the announcement.
What other options do I have?
The other option would have been to use babel as we have been doing for ages. Babel would then transpile our ES6 code to ES5 code and then we can run our server using the transpiled code. I have previously written about using Babel to import/export ES6 modules using Node, but setting up Babel is a pain and an additional step which I would prefer avoiding whenever I can.
John-David Dalton has created a super easy to use npm package called esm which allows you to use tomorrow’s ES6 modules in node today! It is a zero-config solution which just works.
You do not need to do much to use esm in your project. Firstly, you need to install it in your project.
- For new projects, Run
npm init esmor
yarn create esmdepending on which package manager you prefer
- For existing projects,
yarn add esmor
npm install esm.
After that, you need to do is require this package when starting your server with node. For doing so you can use the require command line option when running your server. So for running the node server for the index.js file, you would use the command
node -r esm index.js
If you don’t want to modify the command line parameters, you can require the esm module in a separate file. So, create a new file, say server.js and its contents would be:
require = require("esm")(module/*, options*/)
module.exports = require("./index.js")
And then you can run server.js using node as you normally would.
If you are looking to get some more insights about esm and it’s internals, this video should help you understand more:
Even if you don’t watch it, you are not missing on much. You don’t need to understand the implementation details and can easily keep using import/export for your ES6 modules in node if you followed the steps that I had mentioned above. So go ahead and remove dependencies to babel in your node project now and enjoy writing the future modules today!
Share this post with other fellow node developers to help them avoid the hassle of using commonjs in their node projects.
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Thank you so much!
Welcome. Glad to have helped in some way! Thanks for the comment!
Thanks, but is there’s a way to avoid adding ‘.js’ extension to file names and not get an error message?
Are you talking about the .js in the file name in the require statement?