Improve string split return type of first array index

lib Update Request

Please, consider improving user experience for "".split(...) in cases when string literal is passed, which I believe most users do e.g. split(' ') or split('\n')

Configuration Check

My compilation target is ES2015 and my lib is the default.

Missing / Incorrect Definition

https://github.com/microsoft/TypeScript/blob/b70784ef8f3ba3fd21750b9acf275dd7edcc7fe7/src/lib/es5.d.ts#L460

Essentially duplicate of https://github.com/microsoft/TypeScript/issues/49635, but with https://github.com/microsoft/TypeScript/issues/49635#issuecomment-1163047914 handled:

split<T extends string | RegExp>(separator: T, limit?: number): T extends `${string}${infer U}` ? [string, ...string[]] : string[];

And this should added to param JSDoc then: Only passing `""` and `new RegExp("")` values can result in returning an empty array.

Sample Code

This is super inconvenient when used with destructure:

const [firstLine, ...restLine] = str.split('\n')
// firstLine is possibly undefined, need add exclamation marks everywhere or `as [string, ...string]` above

I also wanted to do the same for when regexp literal is passed e.g. split(/\n\r?/) as only split(new RegExp('')) can result in empty array (if I'm not mistaken), which I believe no one does, but the literal value can't be captured anyway

Documentation Link

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/split#description (note)

P.S. I remembered of this issue after https://github.com/microsoft/TypeScript/pull/49682, which significantly improved type-checking experience by using less exclamation marks

Beginne mit der Deklaration von String.split in src/lib/es5.d.ts ungefähr bei Zeile 460 und sieh dir dann den zugehörigen Issue #49635 und den darin referenzierten Kommentar an. Die Arbeit ist abgeschlossen, wenn der Typ literale nichtleere Trennzeichen als Rückgabe eines Tupels mit einem nichtleeren ersten Element unterscheidet, dabei aber die Fälle mit leeren Arrays beibehält und diese Fälle im Parameter-JSDoc dokumentiert.