Fetch Init
fetch(url, init) — custom method, headers, and request body.
Like examples/fetch/fetch.ts, this talks to a local fixture server (tools/httpbin-lite/, started by `make examples` before this file runs — see) instead of a real external website, so this file needs no real network access and gives deterministic results.
init is any value with some subset of method: string / headers: Map<string,string> | Headers / body: string fields — a plain object works fine here with no Request/Headers class needed, matching how this compiler already represents every other bag of string headers (http.listen's req.headers, a handler's own optional response headers field) as a plain Map<string,string>. Real Request/Headers classes also exist for when you want them — see examples/fetch/fetch_request_headers.ts.
// ── a POST with a JSON body ─────────────────────────────────────────────────
const posted = await fetch('http://127.0.0.1:8765/post', {
method: 'POST',
body: JSON.stringify({ hello: 'world' }),
})
console.log(posted.status) // 200
console.log(posted.text().indexOf('"hello":"world"') > -1) // true — the fixture echoes the body back verbatim
// ── custom headers, sent alongside a GET ────────────────────────────────────
const headers: Map<string, string> = new Map<string, string>()
headers.set('X-Example-Header', 'kml-value')
const withHeaders = await fetch('http://127.0.0.1:8765/headers', { headers: headers })
console.log(withHeaders.text().indexOf('kml-value') > -1) // true — the fixture's /headers echoes every request header back
// ── an explicit method with no body still works (e.g. DELETE) ──────────────
const deleted = await fetch('http://127.0.0.1:8765/delete', { method: 'DELETE' })
console.log(deleted.status) // 200
// ── setting a body without an explicit method sends it as POST ─────────────
// (real, well-known libcurl behavior — CURLOPT_POSTFIELDS implies POST
// unless overridden by an explicit method; confirmed directly, not assumed
// — see ADR-00074's Investigation)
const bodyOnly = await fetch('http://127.0.0.1:8765/post', { body: 'raw-body-text' })
console.log(bodyOnly.text().indexOf('raw-body-text') > -1) // true
// ── fetch(url) with no init argument still works exactly as before ─────────
const plain = await fetch('http://127.0.0.1:8765/get')
console.log(plain.status) // 200