FAQ: Browser Compatibility and Transpilation - Build

This community-built FAQ covers the “Build” exercise from the lesson “Browser Compatibility and Transpilation”.

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This exercise can be found in the following Codecademy content:

Introduction To JavaScript

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In the Browser compatibility and transpilation lesson, part 10: build, after I’ve done everything is the code supposed to switch from ES6 to ES5 because I kinda got the impression that’s what was going to happen, but nothing happened…


The ES5 code should appear in a new main.js file within a new folder lib. I’m reporting a bug that npm run build did not create lib or main.js.


Yep, no lib folder for me, either.


run ls in terminal window and lib will show up in the folder window

type in : nbm run build

Do we need to do anything with the HTML of the website to take advantage of the 2 different code lines? Is there something that we need to include in the header?

Yeah same here! I thought I was doing it wrong, I double checked my JSON but everything is okay

If you set the property value of “build” to “babel src --out dir -d lib” instead of what is recommended in the lesson, you can see the lib folder created in the directory and the transpiled code in the main.js file therein.


I have the same problem. I’ve tried all suggestions posted above and they didn’t work as well. No lib folder created.

After attempting several times (refreshing and resetting) it worked! The lib folder was created.
Don’t ask me why. I checked all the code and it seems the same as before.

It is necessary to put a comma at the end of the “test” script.
(I think…)


To those of you who can’t see lib folder, I was in that case and found how to fix it :

Clic the “Reset Exercise” button, now do the exercise again and it will work without errors.

I guess there is a issue if we come from the previous exercise.

A comma was missiing in the package.json file between scripts : “test” and “build” :wink:


Do not put a , after the “built” object in json file only a , in-between the “test” , “built”

“scripts”: {
“test”: “echo “Error: no test specified” && exit 1”,
“build”:“babel src -d lib”

after that it worked for me!


worked for me, thanks!

this was buggy and confusing.

worked for me, thank you.

Correct! I was looking at the code for a bit and realized the JSON is comma delimited!

Thank you, worked for me too !!

When i try to do the same things like in lesson on my own computer I meet problem like: “couldn’t find preset “env” relative to directory” What can be an issue?