Function buildCandidates

packages/vite/hmr/client/index.ts:904–954

(url: string)

	}
	const baseUrl = getHMRWsUrl() || 'ws://localhost:5173/ns-hmr';
	const buildCandidates = (url: string): string[] => {
		let candidates: string[] = [];
		try {
			const u = new URL(url);
			const proto = u.protocol === 'wss:' ? ['wss'] : ['ws'];
			const defaultPort = u.port || '5173';

			// Build ordered host candidates with preference to the active HTTP origin
			const orderedHosts: Array<{ host: string; port?: string }> = [];
			try {
				const g: any = globalThis as any;
				const httpOrigin: string | undefined = g && typeof g.__NS_HTTP_ORIGIN__ === 'string' ? g.__NS_HTTP_ORIGIN__ : undefined;
				if (httpOrigin) {
					try {
						const ho = new URL(httpOrigin);
						orderedHosts.push({
							host: ho.hostname,
							port: ho.port || defaultPort,
						});
					} catch {}
				}
			} catch {}

			// From provided URL
			orderedHosts.push({ host: u.hostname, port: defaultPort });
			// Explicit override
			try {
				const h = (globalThis as any).__NS_HMR_HOST;
				if (h) orderedHosts.push({ host: String(h), port: defaultPort });
			} catch {}
			// Common fallbacks
			orderedHosts.push({ host: '10.0.2.2', port: defaultPort });
			orderedHosts.push({ host: 'localhost', port: defaultPort });

			const seen = new Set<string>();
			for (const p of proto) {
				for (const { host, port } of orderedHosts) {
					const key = `${host}:${port}`;
					if (seen.has(key)) continue;
					seen.add(key);
					const cand = `${p}://${host}:${port}${u.pathname || '/ns-hmr'}`;
					candidates.push(cand);
				}
			}
		} catch {
			candidates.push(url);
		}
		// Deduplicate while preserving order
		const seen = new Set<string>();
		return candidates.filter((c) => (seen.has(c) ? false : (seen.add(c), true)));
	};

	const candidates = buildCandidates(baseUrl);
	let idx = 0;