Why doesn't babel convert ES6 in one of the modules?

Question

JavaScript

I use this module in the project, I load it via npm.
I connect like this: const striptags = require('striptags') or like this: import striptags from 'striptags';
Contents of the .babelrc project:

{
  "presets": ["es2015", "stage-0", "react"]
}

As a result, in the assembly I see the following lines:

const STATE_PLAINTEXT = Symbol('plaintext');
    const STATE_HTML      = Symbol('html');
    const STATE_COMMENT   = Symbol('comment');
...

That is, ES6 is not processed by babel.
If you copy the script to the project and include it like this:
import striptags from './../utilities/striptags';
Then everything is OK, in the assembly the above lines already look like this:

var STATE_PLAINTEXT = Symbol('plaintext');
    var STATE_HTML = Symbol('html');
    var STATE_COMMENT = Symbol('comment');
...

If you connect directly from node_modules (import striptags from './../../node_modules/striptags/src/striptags';),
then again the conversion does not work.
This only applies to one module. What could be the problem?

Answer 1

Babel will not transpiler node_modules unless it is told to do so in the webpack conf, a
Ups: I'll get to my computer and check your npm module.