I have the following in eslint.config.js in my project:

import globals from "globals";
import pluginJs from "@eslint/js";

export default [{
    languageOptions: {
      globals: globals.browser
    }
  },
  pluginJs.configs.recommended
];

I am working on a main script and a set of other scripts that provide globals.

The index.html imports the files like this:

<script src="js/module1.js"></script>
<script src="js/main.js"></script>

module1.js declares a global:

/* exported my_global */
const my_global = {}

With the configuration above, ESLint gives no-unused-vars error, and picks up a bunch of other errors based on strict rules.

If I change the config to the following:

import globals from "globals";
import pluginJs from "@eslint/js";

export default [{
    languageOptions: {
      globals: globals.browser,
      sourceType: "module",
      ecmaVersion: 5,
      parseOptions: {
        ecmaFeatures: {impliedStrict: false, globalReturn: false, jsx: false}
      }
    }
  },
  pluginJs.configs.recommended
];

Then ESLint shows no errors, ignoring the “exported” global and the various errors in main. I’ve tried impliedStrict: true and sourceType: “script” and the result is the same.

The way I read this documentation it says that these should have identical results, as the new config is just explicitly setting the defaults:

https://eslint.org/docs/latest/use/configure/language-options

Why are they not equivalent?

What I want is to be able to have ESLint generate errors using strict rules but be able to tell it I’m exporting a global so it doesn’t complain about that. I’ve tried the exported comment, “use_strict; and various combinations of config options but I’ve not been able to get the result.

I also asked an overlapping question here:
How do I configure ESLint in VS Code for JS module script