Suggestion: Move `languageOptions` properties from nested `parserOptions`

[DMartens]

What problem do you want to solve?

Currently the playground generates a configuration which specifies sourceType in languageOptions.parserOptions instead of languageOptions. For example:

export default [
    {
        "languageOptions": {
            "parserOptions": {
                "ecmaFeatures": {
                    "jsx": true
                },
                "sourceType": "module"
            },
        }
    }
];

What do you think is the correct solution?

Move the properties languageOptions.parserOptions.{sourceType,ecmaVersion} to languageOptions.{sourceType,ecmaVersion}.

Participation

• I am willing to submit a pull request for this change.

Additional comments

This change would be consistent with the documentation

[mdjermanovic]

I couldn't reproduce this. Here's a Playground with sourceType set to module and jsx enabled, but the config file I'm getting looks like this:

export default [
    {
        "languageOptions": {
            "parserOptions": {
                "ecmaFeatures": {
                    "jsx": true
                }
            },
            "sourceType": "module"
        }
    }
];

"sourceType": "module" appears under "languageOptions", not "parserOptions".

[DMartens]

sourceType only seems to be in parserOptions when using the TypeScript parser ` (I removed that from the example thinking that it was irrelevant).

[lumirlumir]

Friendly ping @mdjermanovic

[mdjermanovic]

This behavior was introduced in #714.

I'm not sure why. @Tanujkanti4441 @snitin315 do you remember why Playground has a special behavior regarding sourceType in case of @typescript-eslint/parser?

[mdjermanovic]

Also, this could be related: selecting script as sourceType doesn't seem to have any effect in the ESLint Playground when parser is @typescript-eslint/parser, probably because of the following code.

eslint.org/src/playground/app.jsx

Lines 176 to 177 in daf7222

	...(options?.languageOptions.parser && {
	sourceType: "module",

For example, with sourceType: "script", this should be a no-implicit-globals lint error on x:

/* eslint no-implicit-globals: 2 */

var x;

However, it doesn't show the lint error in the ESLint Playground:

https://eslint.org/play/#eyJ0ZXh0IjoiLyogZXNsaW50IG5vLWltcGxpY2l0LWdsb2JhbHM6IDIgKi9cblxudmFyIHg7Iiwib3B0aW9ucyI6eyJydWxlcyI6e30sImxhbmd1YWdlT3B0aW9ucyI6eyJwYXJzZXJPcHRpb25zIjp7ImVjbWFGZWF0dXJlcyI6eyJqc3giOnRydWV9LCJzb3VyY2VUeXBlIjoic2NyaXB0In0sInBhcnNlciI6IkB0eXBlc2NyaXB0LWVzbGludC9wYXJzZXIifX19

On the other hand, when I try this code locally with configuration languageOptions: { parser: require("@typescript-eslint/parser"), sourceType: "script" }, it does show the lint error.

The typesscript-eslint Playground also shows the lint error with Source type set to script:

https://typescript-eslint.io/play/#ts=5.9.2&sourceType=script&fileType=.ts&code=PQKgBApgzgNglgOwC5gQewLRwLYAd4DGcSGA5jGgEYCGMUAXGAExgjACwAUFwG7UBOYAB4BuLkA&eslintrc=N4KABGBEBOCuA2BTAzpAXGYBfEWg&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA&tokens=false

So I'm not sure why ESLint Playground effectively ignores sourceType when parser is @typescript-eslint/parser, and why the sourceType property is set on parserOptions instead of languageOptions.

[Tanujkanti4441]

why Playground has a special behavior regarding sourceType in case of @typescript-eslint/parser

This special behavior was suggested based on discussion => eslint/eslint#19563 (comment)

why ESLint Playground effectively ignores sourceType when parser is @typescript-eslint/parser

eslint.org/src/playground/app.jsx

Lines 176 to 177 in daf7222

	...(options?.languageOptions.parser && {
	sourceType: "module",

It seems like a bug, I think we shouldn't have hard-coded sourceType to "module" here. As I tested it locally and it is working as expected when we set sourceType: options.languageOptions.parserOptions.sourceType here.

Or even if we move the sourceType option back to languageOption for tsparser it is working fine.

[xbinaryx]

I think this a bug too. Opened #910.

[mdjermanovic]

This special behavior was suggested based on discussion => eslint/eslint#19563 (comment)

ESLint passes languageOptions.sourceType as parserOptions.sourceType to parsers:

https://github.com/eslint/eslint/blob/63a0c7c84bf5b12357893ea2bf0482aa3c855bac/lib/languages/js/index.js#L245-L271

(unless overridden by languageOptions.parserOptions.sourceType)

I'm not sure why sourceType isn't documented in the @typescript-eslint/parser docs but it's available in the typescript-eslint Playground and has observable effects on the behavior.

So I think we should update the ESLint Playground to remove currently implemented special behavior related to the sourceType option when @typescript-eslint/parser is selected, and so just always use sourceType as languageOptions.sourceType.

Marked as accepted, PR is welcome.