import React from "react";
import { useRouter } from "./router";
const nextjsRouteAnnouncerStyles = {
    border: 0,
    clip: "rect(0 0 0 0)",
    height: "1px",
    margin: "-1px",
    overflow: "hidden",
    padding: 0,
    position: "absolute",
    top: 0,
    width: "1px",
    // https://medium.com/@jessebeach/beware-smushed-off-screen-accessible-text-5952a4c2cbfe
    whiteSpace: "nowrap",
    wordWrap: "normal"
};
export const RouteAnnouncer = ()=>{
    const { asPath } = useRouter();
    const [routeAnnouncement, setRouteAnnouncement] = React.useState("");
    // Only announce the path change, but not for the first load because screen
    // reader will do that automatically.
    const previouslyLoadedPath = React.useRef(asPath);
    // Every time the path changes, announce the new page’s title following this
    // priority: first the document title (from head), otherwise the first h1, or
    // if none of these exist, then the pathname from the URL. This methodology is
    // inspired by Marcy Sutton’s accessible client routing user testing. More
    // information can be found here:
    // https://www.gatsbyjs.com/blog/2019-07-11-user-testing-accessible-client-routing/
    React.useEffect(()=>{
        // If the path hasn't change, we do nothing.
        if (previouslyLoadedPath.current === asPath) return;
        previouslyLoadedPath.current = asPath;
        if (document.title) {
            setRouteAnnouncement(document.title);
        } else {
            const pageHeader = document.querySelector("h1");
            var _pageHeader_innerText;
            const content = (_pageHeader_innerText = pageHeader == null ? void 0 : pageHeader.innerText) != null ? _pageHeader_innerText : pageHeader == null ? void 0 : pageHeader.textContent;
            setRouteAnnouncement(content || asPath);
        }
    }, // TODO: switch to pathname + query object of dynamic route requirements
    [
        asPath
    ]);
    return /*#__PURE__*/ React.createElement("p", {
        "aria-live": "assertive" // Make the announcement immediately.
        ,
        id: "__next-route-announcer__",
        role: "alert",
        style: nextjsRouteAnnouncerStyles
    }, routeAnnouncement);
};
export default RouteAnnouncer;

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