Something went wrong. Try again.
leaflet fork for copy edit / bug fixes forked from leaflet.pub/leaflet
Something went wrong. Try again.
TypeScript
123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990import { useCallback, useRef, useState } from "react";import { useSearchParams } from "next/navigation";
/** * Syncs React state to URL query parameters so filter selections persist * across page refreshes and are shareable via URL. * * Uses `window.history.replaceState` for synchronous URL updates (no * Next.js router transition overhead). Next.js 14+ automatically syncs * its hooks (`useSearchParams`, etc.) when the history API is called. * * Each parameter is defined by a `QueryParam<T>` config that controls how * a value of type `T` is serialized to/from one or more query string keys. * * @example * // Simple string param (?metric=pageviews, default "visitors") * let [metric, setMetric] = useQueryState<"visitors" | "pageviews">({ * toParams: (v) => ({ metric: v === "visitors" ? null : v }), * fromParams: (get) => get("metric") === "pageviews" ? "pageviews" : "visitors", * }); * * // Optional value with multi-key serialization (?post=my-slug) * let [postPath, setPostPath] = useQueryState<string | undefined>({ * fromParams: (get) => get("post") ?? undefined, * toParams: (v) => ({ post: v ?? null }), * }); */
/** Configuration for a single piece of query-synced state. */type QueryParam<T> = { /** * Deserialize from query params → state value. * Called once on mount to initialize from the URL. * Should return the default value when no relevant params are present. * @param get - reads a single query param by key (returns `string | null`) */ fromParams: (get: (key: string) => string | null) => T;
/** * Serialize state value → query param updates. * Return a record of key → string (to set) or key → null (to remove). * Keys set to `null` are deleted from the URL, keeping it clean for defaults. */ toParams: (value: T) => Record<string, string | null>;};
/** * Like `useState`, but the value is initialized from URL query params on mount * and the URL is updated synchronously via `history.replaceState` whenever * the setter is called. * * Returns `[value, setValue]` — a drop-in replacement for `useState`. */export function useQueryState<T>( config: QueryParam<T>,): [T, (value: T) => void] { let searchParams = useSearchParams();
// Use a ref for toParams so the setter callback identity is stable // even when config is an inline object literal. let toParamsRef = useRef(config.toParams); toParamsRef.current = config.toParams;
let [value, _setValue] = useState<T>(() => config.fromParams((key) => searchParams.get(key)), );
let setValue = useCallback((next: T) => { _setValue(next); let updates = toParamsRef.current(next); // Read directly from window.location so we always merge against // the latest URL, even if multiple setters fire in the same frame. let params = new URLSearchParams(window.location.search); for (let [key, v] of Object.entries(updates)) { if (v === null) { params.delete(key); } else { params.set(key, v); } } let qs = params.toString(); let url = qs ? `${window.location.pathname}?${qs}` : window.location.pathname; window.history.replaceState(history.state, "", url); }, []);
return [value, setValue];}