wikimedia/mediawiki-core

/*!
 * In general, MediaWiki does not ask browsers to resolve wiki page
 * redirects client-side over HTTP. Instead, wiki page redirects are
 * resolved server-side and rendered directly in response to a
 * navigation.
 *
 * This script is responsible for:
 *
 * - Update the address bar to reflect the rendered destination.
 *
 *   Given [[Foo]] redirecting to [[Bar]], when viewing [[Foo]]
 *   the server renders Bar content, with "Bar" as doc title
 *   and with "Bar" in the address bar.
 *
 * - For internal redirect destination that specify a fragment, if
 *   the navigation does not set its own fragment, scroll to the
 *   specified section.
 *
 *   Given [[Foo]] redirecting to [[Bar#Foo]], the browser should
 *   scroll to "Foo", and render address bar Bar#Foo (not Foo, Bar,
 *   or Foo#Foo).
 *
 *   Given [[Foo]] redirecting to [[Bar#Foo]], when navigating to
 *   [[Foo#Quux]], the address bar should reflect Bar#Quux, and
 *   let the native scroll happen, don't override scroll to #Foo.
 */
( function () {
    var canonical = mw.config.get( 'wgInternalRedirectTargetUrl' );
    if ( !canonical ) {
        return;
    }

    var fragment = null;
    if ( location.hash ) {
        // Ignore redirect's own fragment and preserve fragment override in address
        canonical = canonical.replace( /#.*$/, '' ) + location.hash;
    } else {
        var index = canonical.indexOf( '#' );
        fragment = ( index !== -1 ) ? canonical.slice( index ) : null;
    }

    // Update address bar, including browser history.
    // Preserve correct "Back"-button behaviour by using replaceState instead of
    // pushState (or location.hash assignment)
    history.replaceState( history.state, '', canonical );

    if ( fragment ) {
        // Specification for history.replaceState() doesn't require browser to scroll,
        // so scroll to be sure (see also T110501).
        var node = document.getElementById( fragment.slice( 1 ) );
        if ( node ) {
            node.scrollIntoView();
        }
    }

}() );