reconsider the defaults of eslint config

[aladdin-add]

things has changed since eslint was created in 2013. It is time to reconsider the defaults of eslint config.
I would suggest the changes:

1. sourceType: "script" => "module"

• native esm has been supported by latest modern browsers and node.js
• a large number of devs are writing esm, and using something like babel/ts to support older browser/node.js versions.

2. ecmaVersion: 5 => "latest"
   we have often got issues like "unexpected token...." just because not config ecmaVersion. e.g. False positive: Unexpected token , #11643
   the change should be good for users & maintainers.

3. --ext: ".js" => ".js,.mjs,.cjs"

it is a breaking change, but it's very easy to restore the old behaviour

{
  "parserOptions": {"ecmaVersion": 5, "sourceType": "script",}
}

if we agreed to the change, document & eslint --init should be updated to reflect the change, too.

[nzakas]

We can consider this when we move to flat config. Changing this for eslintrc is likely to break a lot of existing users’ configurations.

[btmills]

I like @nzakas' idea. Flat config gives us a chance to update defaults in a way that likely reduces migration difficulty.

[aladdin-add]

agreed. I will update the OP later.

[github-actions]

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[nzakas]

I’ll handle this as I’m working on the new config.

[nzakas]

Fixed in #15185