Environment

Node version: 22.15.1
npm version: 10.9.2
Local ESLint version: 9.28.0
Global ESLint version: N/A
Operating System: macOS Sequoia 15.5

What parser are you using?

Default (Espree)

What did you do?

In my TypeScript (5.7.3) project, I'm trying to programmatically call Linter.verifyAndFix(code, config, options), specifying the filterCodeBlock property of options since my plugin takes both JS and HTML files.

The LintOptions interface in lib/types/index.d.ts specifies filterCodeBlock's type as boolean | undefined. filterCodeBlock should be a function type that returns a boolean.

And indeed, if you try to run Linter.verifyAndFix() with filterCodeBlock set to e.g. true (as its specified type would suggest), you get the following error when the linter tries to run that (non-)function:

TypeError: filterCodeBlock is not a function

What did you expect to happen?

In TypeScript I expect to be able to specify filterCodeBlock as a function type that returns a boolean, not as a boolean property itself. I can get around this by creating my function type, then casting it to boolean, a la:

{ filename: 'myFile.html', filterCodeBlock: myFilterCodeBlock as unknown as boolean }

That makes the code function. But that's clearly not the intent of the type interface.

What actually happened?

Having to set filterCodeBlock as a boolean makes Linter.verifyAndFix() throw a TypeError at runtime.

Link to Minimal Reproducible Example

https://eslint.org/play/#eyJ0ZXh0IjoiaW1wb3J0IHsgTGludGVyIH0gZnJvbSAnZXNsaW50Jztcbi8vIGNvbnN0IGpzVG9BbmFseXplID0gJ3ZvaWQgMDsnO1xuY29uc3QgaHRtbFRvQW5hbHl6ZSA9ICc8aHRtbD48Ym9keT48cD5IZWxsbyB3b3JsZDwvcD48L2JvZHk+PC9odG1sPidcbmNvbnN0IHByb2Nlc3NvciA9IHtcbiAgcHJlcHJvY2VzczogKHRleHQsIGZpbGVuYW1lKSA9PiB7XG4gICAgaWYgKGZpbGVuYW1lLmVuZHNXaXRoKCcuanMnKSkge1xuICAgICAgcmV0dXJuIFt7IHRleHQsIGZpbGVuYW1lIH1dO1xuICAgIH0gZWxzZSB7XG4gICAgICByZXR1cm4gW3sgdGV4dDogJycsIGZpbGVuYW1lIH1dO1xuICAgIH1cbiAgfSxcbiAgcG9zdHByb2Nlc3M6IChtZXNzYWdlcykgPT4ge1xuICAgIHJldHVybiBtZXNzYWdlcy5mbGF0KCk7XG4gIH1cbn1cbmNvbnN0IGxpbnRlciA9IG5ldyBMaW50ZXIoKTtcbi8vIGNvbnN0IGZpbHRlckNvZGVCbG9ja0dvb2QgPSAoYmxvY2tGaWxlbmFtZSkgPT4ge1xuLy8gICByZXR1cm4gYmxvY2tGaWxlbmFtZS5lbmRzV2l0aChcIi5qc1wiKSB8fCBibG9ja0ZpbGVuYW1lLmVuZHNXaXRoKFwiLmh0bWxcIik7XG4vLyB9O1xuY29uc3QgZmlsdGVyQ29kZUJsb2NrQmFkID0gdHJ1ZTtcbmxpbnRlci52ZXJpZnlBbmRGaXgoaHRtbFRvQW5hbHl6ZSwge1xuICBmaWxlczogW1wiKi5qc1wiLCBcIioqLyouanNcIiwgXCIqLmh0bWxcIiwgXCIqKi8qLmh0bWxcIl0sXG4gIHByb2Nlc3Nvcixcbn0sIHtcbiAgICBmaWxlbmFtZTogJ215SHRtbC5odG1sJyxcbiAgICBmaWx0ZXJDb2RlQmxvY2s6IGZpbHRlckNvZGVCbG9ja0JhZCxcbiAgfVxuKTsiLCJvcHRpb25zIjp7InJ1bGVzIjp7ImNvbnN0cnVjdG9yLXN1cGVyIjpbImVycm9yIl0sImZvci1kaXJlY3Rpb24iOlsiZXJyb3IiXSwiZ2V0dGVyLXJldHVybiI6WyJlcnJvciJdLCJuby1hc3luYy1wcm9taXNlLWV4ZWN1dG9yIjpbImVycm9yIl0sIm5vLWNhc2UtZGVjbGFyYXRpb25zIjpbImVycm9yIl0sIm5vLWNsYXNzLWFzc2lnbiI6WyJlcnJvciJdLCJuby1jb21wYXJlLW5lZy16ZXJvIjpbImVycm9yIl0sIm5vLWNvbmQtYXNzaWduIjpbImVycm9yIl0sIm5vLWNvbnN0LWFzc2lnbiI6WyJlcnJvciJdLCJuby1jb25zdGFudC1iaW5hcnktZXhwcmVzc2lvbiI6WyJlcnJvciJdLCJuby1jb25zdGFudC1jb25kaXRpb24iOlsiZXJyb3IiXSwibm8tY29udHJvbC1yZWdleCI6WyJlcnJvciJdLCJuby1kZWJ1Z2dlciI6WyJlcnJvciJdLCJuby1kZWxldGUtdmFyIjpbImVycm9yIl0sIm5vLWR1cGUtYXJncyI6WyJlcnJvciJdLCJuby1kdXBlLWNsYXNzLW1lbWJlcnMiOlsiZXJyb3IiXSwibm8tZHVwZS1lbHNlLWlmIjpbImVycm9yIl0sIm5vLWR1cGUta2V5cyI6WyJlcnJvciJdLCJuby1kdXBsaWNhdGUtY2FzZSI6WyJlcnJvciJdLCJuby1lbXB0eSI6WyJlcnJvciJdLCJuby1lbXB0eS1jaGFyYWN0ZXItY2xhc3MiOlsiZXJyb3IiXSwibm8tZW1wdHktcGF0dGVybiI6WyJlcnJvciJdLCJuby1lbXB0eS1zdGF0aWMtYmxvY2siOlsiZXJyb3IiXSwibm8tZXgtYXNzaWduIjpbImVycm9yIl0sIm5vLWV4dHJhLWJvb2xlYW4tY2FzdCI6WyJlcnJvciJdLCJuby1mYWxsdGhyb3VnaCI6WyJlcnJvciJdLCJuby1mdW5jLWFzc2lnbiI6WyJlcnJvciJdLCJuby1nbG9iYWwtYXNzaWduIjpbImVycm9yIl0sIm5vLWltcG9ydC1hc3NpZ24iOlsiZXJyb3IiXSwibm8taW52YWxpZC1yZWdleHAiOlsiZXJyb3IiXSwibm8taXJyZWd1bGFyLXdoaXRlc3BhY2UiOlsiZXJyb3IiXSwibm8tbG9zcy1vZi1wcmVjaXNpb24iOlsiZXJyb3IiXSwibm8tbWlzbGVhZGluZy1jaGFyYWN0ZXItY2xhc3MiOlsiZXJyb3IiXSwibm8tbmV3LW5hdGl2ZS1ub25jb25zdHJ1Y3RvciI6WyJlcnJvciJdLCJuby1ub25vY3RhbC1kZWNpbWFsLWVzY2FwZSI6WyJlcnJvciJdLCJuby1vYmotY2FsbHMiOlsiZXJyb3IiXSwibm8tb2N0YWwiOlsiZXJyb3IiXSwibm8tcHJvdG90eXBlLWJ1aWx0aW5zIjpbImVycm9yIl0sIm5vLXJlZGVjbGFyZSI6WyJlcnJvciJdLCJuby1yZWdleC1zcGFjZXMiOlsiZXJyb3IiXSwibm8tc2VsZi1hc3NpZ24iOlsiZXJyb3IiXSwibm8tc2V0dGVyLXJldHVybiI6WyJlcnJvciJdLCJuby1zaGFkb3ctcmVzdHJpY3RlZC1uYW1lcyI6WyJlcnJvciJdLCJuby1zcGFyc2UtYXJyYXlzIjpbImVycm9yIl0sIm5vLXRoaXMtYmVmb3JlLXN1cGVyIjpbImVycm9yIl0sIm5vLXVuZGVmIjpbImVycm9yIl0sIm5vLXVuZXhwZWN0ZWQtbXVsdGlsaW5lIjpbImVycm9yIl0sIm5vLXVucmVhY2hhYmxlIjpbImVycm9yIl0sIm5vLXVuc2FmZS1maW5hbGx5IjpbImVycm9yIl0sIm5vLXVuc2FmZS1uZWdhdGlvbiI6WyJlcnJvciJdLCJuby11bnNhZmUtb3B0aW9uYWwtY2hhaW5pbmciOlsiZXJyb3IiXSwibm8tdW51c2VkLWxhYmVscyI6WyJlcnJvciJdLCJuby11bnVzZWQtcHJpdmF0ZS1jbGFzcy1tZW1iZXJzIjpbImVycm9yIl0sIm5vLXVudXNlZC12YXJzIjpbImVycm9yIl0sIm5vLXVzZWxlc3MtYmFja3JlZmVyZW5jZSI6WyJlcnJvciJdLCJuby11c2VsZXNzLWNhdGNoIjpbImVycm9yIl0sIm5vLXVzZWxlc3MtZXNjYXBlIjpbImVycm9yIl0sIm5vLXdpdGgiOlsiZXJyb3IiXSwicmVxdWlyZS15aWVsZCI6WyJlcnJvciJdLCJ1c2UtaXNuYW4iOlsiZXJyb3IiXSwidmFsaWQtdHlwZW9mIjpbImVycm9yIl19LCJsYW5ndWFnZU9wdGlvbnMiOnsicGFyc2VyT3B0aW9ucyI6eyJlY21hRmVhdHVyZXMiOnt9fX19fQ==

Participation

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

Additional comments

No response