fix(react): infer constructor return type instead of void

[pmarkert]

Description

generateSignature fell back to void whenever an entry had no Returns:
line. Node's API docs omit that line on constructors by convention, so every
constructor rendered as returning void — e.g. new Agent(options?): void on
http.html. A
constructor never returns void; it yields an instance of its own class.

The third parameter of generateSignature / createSignatureCodeBlock was a
prefix string ('new '). It now takes the heading's HeadingData instead, so
the function derives both the prefix and the return-type fallback from the
heading type rather than having them passed in pre-computed. Constructors fall
back to their own class name; everything else still falls back to void.

This also fixes a smaller related bug: a Returns: entry that exists but has
no parsable type rendered the literal string undefined, and now falls back to
void.

Note for reviewers: the old signature accepted an arbitrary prefix string, and a
test covered 'abstract '. That value was never a HeadingType, no caller ever
produced it, and its output (class abstract MyClass extends BaseClass) is not
valid TypeScript — so it was covering an unreachable branch. That test now
asserts a class heading renders with no prefix.

Validation

node --run test — 553 passing, 0 failing. Rewrote the three tests that
exercised the old string-prefix contract, and added coverage for: a constructor
with no Returns:, a constructor with an explicit Returns: (inference must
not clobber it), and a return entry with no type.

Rendered locally with -t web and diffed the signature lines against
beta.docs.nodejs.org:

	before	after
http.html	new Agent(options?): void	new Agent(options?): Agent
url.html	new URL(input, base?): void	new URL(input, base?): URL
sqlite.html	new DatabaseSync(path, options?): void	new DatabaseSync(path, options?): DatabaseSync
net.html	new net.SocketAddress(options?): void	new net.SocketAddress(options?): net.SocketAddress

Also verified unchanged: agent.destroy(): void and other genuinely-void
methods still render void; all five class X extends Y signatures in
http.html are untouched; the five new Buffer(...) overloads each keep their
own distinct parameters.

Where a page already had an explicit Returns: on its constructor
(net.Server, net.Socket), the inferred value matches it exactly.

One judgment call worth a maintainer's opinion: the fallback uses the displayed
name, so http.md renders : Agent while net.md renders : net.Socket —
consistent within each page, but not across them, because the headings differ
(### new Agent(...) vs ### new net.Socket(...)). Happy to normalise if
you'd prefer.

Related Issues

Addresses #953 — the constructor
bullets (net, buffer, fs, http, sqlite, url). The remaining items in
that issue (overloads only annotating the last signature, async-dispose methods,
and source-side missing Returns: lines) are untouched.

Check List

• I have read the Contributing Guidelines and made commit messages that follow the guideline.
• I have run node --run test and all tests passed.
• I have check code formatting with node --run format:check & node --run lint.
• I've covered new added functionality with unit tests if necessary.

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Project	Deployment	Actions	Updated (UTC)
api-docs-tooling	Ready	Preview	Aug 13, 2026 8:43pm