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perf(map): preload map chunk at module level with tile CDN hints #15

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Merged
ronload merged 1 commit into from
Apr 15, 2026
Merged

perf(map): preload map chunk at module level with tile CDN hints #15

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14 changes: 14 additions & 0 deletions src/app/layout.tsx
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Original file line number Diff line number Diff line change
Expand Up @@ -68,6 +68,20 @@ export default function RootLayout({
suppressHydrationWarning
className={`${geistSans.variable} ${geistMono.variable} h-full antialiased`}
>
<head>
<link
rel="preconnect"
href="https://basemaps.cartocdn.com"
crossOrigin="anonymous"
/>
<link
rel="preconnect"
href="https://tiles.basemaps.cartocdn.com"
crossOrigin="anonymous"
/>
<link rel="dns-prefetch" href="https://basemaps.cartocdn.com" />
<link rel="dns-prefetch" href="https://tiles.basemaps.cartocdn.com" />
</head>
<body className="flex min-h-full flex-col">
<ThemeProvider
attribute="class"
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55 changes: 30 additions & 25 deletions src/components/address-page.tsx
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Original file line number Diff line number Diff line change
@@ -1,21 +1,25 @@
"use client";

import { useEffect, useState } from "react";
import dynamic from "next/dynamic";
import { useEffect, useState, type ComponentType } from "react";
import type { City } from "@/lib/types";
import { useAddressState } from "@/hooks/use-address-state";
import { useMediaQuery } from "@/hooks/use-media-query";
import { AddressForm } from "@/components/address-form";

const TaiwanMap = dynamic(
() => import("@/components/taiwan-map").then((m) => m.TaiwanMap),
{
ssr: false,
loading: () => (
<div className="border-border/50 bg-muted/30 h-full w-full animate-pulse rounded-xl border" />
),
},
);
// Module-level: start downloading the map chunk during hydration (before any
// useEffect fires). Only on desktop to avoid wasting mobile bandwidth.
// Also prime the HTTP cache for counties data in parallel.
const isDesktopAtLoad =
typeof window !== "undefined" &&
window.matchMedia("(min-width: 1024px)").matches;

const mapModulePromise = isDesktopAtLoad
? import("@/components/taiwan-map")
: null;

if (isDesktopAtLoad) {
void fetch("/data/map/counties-10t.json");
}

const MapPlaceholder = () => (
<div className="border-border/50 bg-muted/30 h-full w-full animate-pulse rounded-xl border" />
Expand All @@ -28,25 +32,26 @@ interface AddressPageProps {
export function AddressPage({ cities }: AddressPageProps) {
const addressState = useAddressState();
const isDesktop = useMediaQuery("(min-width: 1024px)");
const [mapReady, setMapReady] = useState(false);
// eslint-disable-next-line @typescript-eslint/no-explicit-any
const [TaiwanMap, setTaiwanMap] = useState<ComponentType<any> | null>(null);

useEffect(() => {
if (!isDesktop) return;

if (typeof requestIdleCallback === "function") {
const id = requestIdleCallback(() => {
setMapReady(true);
});
return () => {
cancelIdleCallback(id);
};
}
let cancelled = false;

// If the module-level preload started, reuse that promise;
// otherwise start a fresh download (e.g. viewport was resized to desktop).
const promise = mapModulePromise ?? import("@/components/taiwan-map");

void promise.then((mod) => {
if (!cancelled) {
setTaiwanMap(() => mod.TaiwanMap);
}
});

const id = setTimeout(() => {
setMapReady(true);
}, 0);
return () => {
clearTimeout(id);
cancelled = true;
};
}, [isDesktop]);

Expand All @@ -56,7 +61,7 @@ export function AddressPage({ cities }: AddressPageProps) {
{isDesktop && (
<div>
<div className="sticky top-16 h-[calc(100vh-8rem)]">
{mapReady ? (
{TaiwanMap ? (
<TaiwanMap
city={addressState.state.city}
district={addressState.state.district}
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