If I don't specify any Babel plugins or presets, what exactly should happen?

[Carl Gross]

What exactly will happen if I run Babelify with no presets or plugins specified, e.g. this command:

node_modules/.bin/browserify file-a.js file-b.js -t [ babelify ] --outfile outfile.js

The documentation seems to say that Babelify will 'not do anything.' I say that because

• The Babelify GitHub repo says, "For babelify to be useful, you must also include some presets and/or plugins."
• The Babel plugins page says, "Now, out of the box Babel doesn't do anything."

The reason I ask is because in my case, when I run the above Browserify command, it seems to do something. I will explain below.

I created two test JS files: file-a.js and file-b.js. Here are the contents of each:

• file-a.js contents

const testFile = require('../www/js/functions.js')

• file-b.js contents

import 'regenerator-runtime/runtime'

From the command line, if I execute:

node file-a.js

it fails with:

import 'regenerator-runtime/runtime'
^^^^^^
SyntaxError: Cannot use import statement outside a module

Then, I bundle both files with the following Browserify command with a Babelify transform (note there are no plugins/presets explicitly specified):

node_modules/.bin/browserify file-a.js file-b.js -t [ babelify ] --outfile outfile.js

After, I run the command:

node outfile.js

it now completes without error. So bundling both files with Browserify, with a Babelify transform, and omitting plugins/presets, seemed to resolve the issue.

So what is happening in my case? If I omit plugins/presets, are there default plugins that are used? Or am I misunderstanding something?

---

Note

--If I remove the Babelify transform from the Browserify command, then run node outfile.js it fails with:

C:\Users\snarl\Orbis\osatest\www\js\functions.js:3

import 'regenerator-runtime/runtime'
^

ParseError: 'import' and 'export' may appear only with 'sourceType: module'*

--I am using Browserify v16.5.1 and Babelify v10.0.0.

Thanks.

[Renée]

It sounds like there's a babel config file somewhere. Plugins specified on the command line are combined with the plugins specified in the nearest babel config file.

[Carl Gross]

OK thanks for that info. Here's what I found in terms of Babel config files:

• In the root of my project is a file babel.config.json, which contains only:

{
    "presets": [
        "@babel/preset-env"
    ]
}

So is this to say that in my case, when Babel carries out its transform, it uses at least this particular preset? It sounds like 'yes' :-)

• In my Windows home directory for this particular user is the file .babel.json. It is rather long, and there is a plugins key which appears twice in the file. But I'm not sure how to interpret the value of this key. Here is a pastebin . Is it relevant in this case? If so, what is it telling us about the Babel transform? In the same file, the presets key has a blank array as a value.

• In my project's package.json there are no babel keys.

[Renée]

~/.babel.json I think is some kind of cache file. babel.config.json is the one that will be picked up by babelify or any other babel tool. https://babeljs.io/docs/en/config-files

[Carl Gross]

OK thanks. So in babel.config.json let's say I remove that presets key. What should then occur if I execute the same browserify command?

[Renée]

The files are still passed through babel, but without any plugins, so it will just output the same code as you put in (save for formatting changes).

[Carl Gross]

OK thanks for all the info--I appreciate it. We can consider this resolved.