[Kenta Moriuchi (petamoriken)]

Fixes #48523

[Jake Bailey (jakebailey)]

This is a nit, but it looks like every other lib d.ts file is formatted with four spaces, the standard we use in this repo, while the file added here uses two.

[Leo. (leoriviera)]

Taking a looking at the MDN article for this, the locale is optional, meaning the first argument may be an object containing options for the segmenter.

[Jake Bailey (jakebailey)]

The syntax section implies that you have to provide locales if you want to supply options. The definition in this PR already makes it optional in that way (pass undefined).

If you pass an options object as the first parameter, the Segmenter you get back doesn't work properly, so I don't think that's correct (even if it doesn't crash). Try deleting 'fr' from the code example on the page and run it, then compare if you pass undefined.

[Leo. (leoriviera)]

I did weigh up the syntax section when writing that comment. Thank you for clarifying my understanding of this. I really appreciate it.