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class="sidebar-filter-container"><div class="sidebar-filter "><label id="sidebar-filter-label" class="sidebar-filter-label" for="sidebar-filter-input"><span class="icon icon-filter"></span><span class="visually-hidden">Filter sidebar</span></label><input id="sidebar-filter-input" autoComplete="off" class="sidebar-filter-input-field false" type="text" placeholder="Filter" value=""/><button type="button" class="button action has-icon clear-sidebar-filter-button"><span class="button-wrap"><span class="icon icon-cancel "></span><span class="visually-hidden">Clear filter input</span></span></button></div></section></header><div class="sidebar-inner-nav"><div class="in-nav-toc"><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In diesem Artikel</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#protokollieren_von_anfrage-urls">Protokollieren von Anfrage-URLs</a></li><li class="document-toc-item "><a class="document-toc-link" href="#umleiten_von_anfragen">Umleiten von Anfragen</a></li><li class="document-toc-item "><a class="document-toc-link" href="#ändern_von_anfrage-headern">Ändern von Anfrage-Headern</a></li><li class="document-toc-item "><a class="document-toc-link" href="#mehr_erfahren">Mehr erfahren</a></li></ul></section></div></div><div class="sidebar-body"> <ol> <li class="section"><a href="/de/docs/Mozilla/Add-ons/WebExtensions">Browsererweiterungen</a></li> <li> <details> <summary>Erste Schritte</summary> <ol> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/What_are_WebExtensions">Was sind Erweiterungen?</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Your_first_WebExtension">Ihre erste Erweiterung</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension">Ihre zweite Erweiterung</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Anatomy_of_a_WebExtension">Anatomie einer Erweiterung</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Examples">Beispielerweiterungen</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/What_next">Was nun?</a></li> </ol> </details> </li> <li> <details> <summary>Konzepte</summary> <ol> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API">JavaScript-APIs</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Content_scripts">Content scripts</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Background_scripts">Hintergrundskripte</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns">Match patterns</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Working_with_files">Arbeiten mit Dateien</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Internationalization">Internationalisierung</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Content_Security_Policy">Content Security Policy</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Native_messaging">Native messaging</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations">Unterschiede zwischen API-Implementierungen</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Chrome_incompatibilities">Chrome-Inkompatibilitäten</a></li> </ol> </details> </li> <li> <details> <summary>Benutzeroberfläche</summary> <ol> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface">Benutzeroberfläche</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Toolbar_button">Toolbar-Button</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Page_actions">Adressleisten-Schaltfläche</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Sidebars">Seitenleisten</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Context_menu_items">Kontextmenüelemente</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Options_pages">Options page</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Extension_pages">Erweiterungsseiten</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Notifications">Notifications</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Omnibox">Address bar suggestions</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/devtools_panels">devtools panels</a></li> </ol> </details> </li> <li> <details open=""> <summary>Anleitungen</summary> <ol> <li><em><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests" aria-current="page">HTTP-Anfragen abfangen</a></em></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Modify_a_web_page">Eine Webseite modifizieren</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Safely_inserting_external_content_into_a_page">Externe Inhalte einfügen</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Sharing_objects_with_page_scripts">Objekte mit Seitenskripts teilen</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Add_a_button_to_the_toolbar">Einen Button zur Toolbar hinzufügen</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Implement_a_settings_page">Implementieren einer Einstellungsseite</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Working_with_the_Tabs_API">Arbeiten mit der Tabs-API</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_the_Bookmarks_API">Arbeiten mit der Bookmarks API</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_the_Cookies_API">Arbeiten mit der Cookies-API</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_contextual_identities">Arbeiten mit kontextbezogenen Identitäten</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Interact_with_the_clipboard">Interagieren mit der Zwischenablage</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Extending_the_developer_tools">Erweiterung der Entwicklerwerkzeuge</a></li> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension">Erstellen Sie eine plattformübergreifende Browser-Erweiterung</a></li> </ol> </details> </li> <li> <details> <summary>JavaScript-APIs</summary> <ol><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/Browser_support_for_JavaScript_APIs">Browser support for JavaScript APIs</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/action">action</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/alarms">alarms</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/bookmarks">bookmarks</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/browserAction">browserAction</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/browserSettings">browserSettings</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/browsingData">browsingData</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/captivePortal">captivePortal</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/clipboard">clipboard</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/commands">commands</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/contentScripts">contentScripts</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/contextualIdentities">contextualIdentities</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/cookies">cookies</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest">declarativeNetRequest</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/devtools">devtools</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/dns">dns</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/dom">dom</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/downloads">downloads</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/events">events</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/extension">extension</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/extensionTypes">extensionTypes</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/find">find</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/history">history</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/i18n">i18n</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/identity">identity</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/idle">idle</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/management">management</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/menus">menus</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/notifications">notifications</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/omnibox">omnibox</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/pageAction">pageAction</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/permissions">permissions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/pkcs11">pkcs11</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/privacy">privacy</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/proxy">proxy</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/runtime">runtime</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/scripting">scripting</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/search">search</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/sessions">sessions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/sidebarAction">sidebarAction</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/storage">storage</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/tabs">tabs</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/theme">theme</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/topSites">topSites</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/types">types</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/userScripts">userScripts</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webNavigation">webNavigation</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest">webRequest</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/windows">windows</a></li></ol> </details> </li> <li> <details> <summary>Manifest-Schlüssel</summary> <ol> <li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json">manifest.json</a></li> </ol> <ol><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/action">action</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/author">author</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/background">background</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_action">browser_action</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_specific_settings">browser_specific_settings</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/chrome_settings_overrides">chrome_settings_overrides</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/chrome_url_overrides">chrome_url_overrides</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/commands">commands</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_scripts">content_scripts</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_security_policy">content_security_policy</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/declarative_net_request">declarative_net_request</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/default_locale">default_locale</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/description">description</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/developer">developer</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/devtools_page">devtools_page</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/dictionaries">dictionaries</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/externally_connectable">externally_connectable</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/homepage_url">homepage_url</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/host_permissions">host_permissions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/icons">icons</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/incognito">incognito</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/manifest_version">manifest_version</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/name">name</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/offline_enabled">offline_enabled</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/omnibox">omnibox</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/optional_host_permissions">optional_host_permissions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/optional_permissions">optional_permissions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/options_page">options_page</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/options_ui">options_ui</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/page_action">page_action</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions">permissions</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/protocol_handlers">protocol_handlers</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/short_name">short_name</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/sidebar_action">sidebar_action</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/storage">storage</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme">theme</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme_experiment">theme_experiment</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/user_scripts">user_scripts</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/version">version</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/version_name">version_name</a></li><li><a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/web_accessible_resources">web_accessible_resources</a></li></ol> </details> </li> <li> <details> <summary>Erweiterungs-Workshop</summary> <ol> <li><a href="https://extensionworkshop.com/documentation/develop/">Entwickeln</a></li> <li><a href="https://extensionworkshop.com/documentation/publish/">Veröffentlichen</a></li> <li><a href="https://extensionworkshop.com/documentation/manage/">Verwalten</a></li> <li><a href="https://extensionworkshop.com/documentation/enterprise/">Unternehmen</a></li> </ol> </details> </li> <li class="section"><a href="/de/docs/Mozilla/Add-ons/Contact_us">Kontaktieren Sie uns</a></li> <li> <details> <summary>Kanäle</summary> <ol> <li><a href="https://blog.mozilla.org/addons">Add-ons Blog</a></li> <li><a href="https://discourse.mozilla.org/c/add-ons">Add-ons Forum</a></li> <li><a href="https://chat.mozilla.org/#/room/%23addons:mozilla.org">Add-ons Chat</a></li> </ol> </details> </li> </ol> </div></div><section class="place side"></section></nav></aside><div class="toc-container"><aside class="toc"><nav><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In diesem Artikel</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#protokollieren_von_anfrage-urls">Protokollieren von Anfrage-URLs</a></li><li class="document-toc-item "><a class="document-toc-link" href="#umleiten_von_anfragen">Umleiten von Anfragen</a></li><li class="document-toc-item "><a class="document-toc-link" href="#ändern_von_anfrage-headern">Ändern von Anfrage-Headern</a></li><li class="document-toc-item "><a class="document-toc-link" href="#mehr_erfahren">Mehr erfahren</a></li></ul></section></div></nav></aside><section class="place side"></section></div></div><main id="content" class="main-content "><article class="main-page-content" lang="de"><header><h1>HTTP-Anfragen abfangen</h1></header><div class="section-content"><p> Um HTTP-Anfragen abzufangen, verwenden Sie die <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest"><code>webRequest</code></a> API. Mit dieser API können Sie Listener für verschiedene Phasen einer HTTP-Anfrage hinzufügen. In den Listenern können Sie: </p> <ul> <li>Zugriff auf Anfrage- und Antwort-Header und -Körper erhalten.</li> <li>Anfragen abbrechen und umleiten.</li> <li>Anfrage- und Antwort-Header ändern.</li> </ul> <p>Dieser Artikel untersucht drei verschiedene Verwendungen des <code>webRequest</code> Moduls:</p> <ul> <li>Protokollieren von Anfrage-URLs, wenn sie gemacht werden.</li> <li>Umleiten von Anfragen.</li> <li>Ändern von Anfrage-Headern.</li> </ul></div><section aria-labelledby="protokollieren_von_anfrage-urls"><h2 id="protokollieren_von_anfrage-urls"><a href="#protokollieren_von_anfrage-urls">Protokollieren von Anfrage-URLs</a></h2><div class="section-content"><p> Um zu sehen, wie Sie <code>webRequest</code> verwenden können, um Anfragen zu protokollieren, erstellen Sie ein neues Verzeichnis namens "requests". Erstellen Sie in diesem Verzeichnis eine Datei namens "manifest.json" und fügen Sie hinzu: </p> <div class="code-example"><div class="example-header"><span class="language-name">json</span></div><pre class="brush: json notranslate"><code>{ "description": "Demonstrating webRequests", "manifest_version": 2, "name": "webRequest-demo", "version": "1.0", "permissions": ["webRequest", "<all_urls>"], "background": { "scripts": ["background.js"] } } </code></pre></div> <p>Erstellen Sie als nächstes eine Datei namens "background.js" und fügen Sie hinzu:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>function logURL(requestDetails) { console.log(`Loading: ${requestDetails.url}`); } browser.webRequest.onBeforeRequest.addListener(logURL, { urls: ["<all_urls>"], }); </code></pre></div> <p> Sie verwenden <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest"><code>onBeforeRequest</code></a>, um die <code>logURL()</code> Funktion unmittelbar vor Beginn der Anfrage aufzurufen. Die <code>logURL()</code> Funktion erfasst die URL der Anfrage aus dem Ereignisobjekt und protokolliert sie in der Browser-Konsole. Das <code>{urls: ["<all_urls>"]}</code> <a href="/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns">Muster</a> bedeutet, dass Sie HTTP-Anfragen an alle URLs abfangen. </p> <p>Um dies zu testen:</p> <ul> <li> <p><a href="https://extensionworkshop.com/documentation/develop/temporary-installation-in-firefox/" class="external" target="_blank">Installieren Sie die Erweiterung</a></p> </li> <li> <p>Öffnen Sie die <a href="https://firefox-source-docs.mozilla.org/devtools-user/browser_console/" class="external" target="_blank">Browser-Konsole</a> (verwenden Sie <kbd>Ctrl + Shift + J</kbd>)</p> </li> <li> <p>Aktivieren Sie <em>Show Content Messages</em> im Menü:</p> <p> <img src="/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/browser_console_show_content_messages.png" alt="Browser console menu: Show Content Messages" width="456" height="340" loading="lazy"> </p> </li> <li> <p>Öffnen Sie einige Webseiten.</p> </li> </ul> <p> In der Browser-Konsole sollten Sie die URLs für Ressourcen sehen, die der Browser anfragt. Zum Beispiel zeigt dieser Screenshot die URLs vom Laden einer Wikipedia-Seite: </p> <p> <img src="/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/browser_console_url_from_extension.png" alt="Browser console menu: URLs from extension" width="795" height="480" loading="lazy"> </p></div></section><section aria-labelledby="umleiten_von_anfragen"><h2 id="umleiten_von_anfragen"><a href="#umleiten_von_anfragen">Umleiten von Anfragen</a></h2><div class="section-content"><p>Verwenden Sie nun <code>webRequest</code>, um HTTP-Anfragen umzuleiten. Ersetzen Sie zuerst "manifest.json" mit diesem:</p> <div class="code-example"><div class="example-header"><span class="language-name">json</span></div><pre class="brush: json notranslate"><code>{ "description": "Demonstrating webRequests", "manifest_version": 2, "name": "webRequest-demo", "version": "1.0", "permissions": [ "webRequest", "webRequestBlocking", "https://developer.mozilla.org/" ], "background": { "scripts": ["background.js"] } } </code></pre></div> <p>Die Änderungen hier:</p> <ul> <li> Fügen Sie die <code>webRequestBlocking</code> <a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions"><code>permission</code></a> hinzu. Diese zusätzliche Berechtigung wird benötigt, wenn eine Erweiterung eine Anfrage ändern möchte. </li> <li>Ersetzen Sie die <code><all_urls></code> Berechtigung durch einzelne <a href="/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions#host_permissions">host permissions</a>, da es gute Praxis ist, die Anzahl der angeforderten Berechtigungen zu minimieren.</li> </ul> <p>Ersetzen Sie als nächstes "background.js" mit diesem:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>let pattern = "https://developer.mozilla.org/*"; const targetUrl = "https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension/frog.jpg"; function redirect(requestDetails) { console.log(`Redirecting: ${requestDetails.url}`); if (requestDetails.url === targetUrl) { return; } return { redirectUrl: targetUrl, }; } browser.webRequest.onBeforeRequest.addListener( redirect, { urls: [pattern], types: ["image"] }, ["blocking"], ); </code></pre></div> <p> Auch hier verwenden Sie den <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest"><code>onBeforeRequest</code></a> Event-Listener, um eine Funktion unmittelbar vor jeder Anfrage auszuführen. Diese Funktion ersetzt die <code>redirectUrl</code> mit der Ziel-URL, die in der Funktion angegeben ist. In diesem Fall das Froschbild aus dem <a href="/de/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension">Tutorial für Ihre zweite Erweiterung</a>. </p> <p> Diesmal fangen Sie nicht jede Anfrage ab: die Option <code>{urls:[pattern], types:["image"]}</code> gibt an, dass Sie nur Anfragen (1) an URLs unter "<a href="/">https://developer.mozilla.org/</a>" und (2) für Bildressourcen abfangen. Weitere Informationen hierzu finden Sie unter <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/RequestFilter"><code>webRequest.RequestFilter</code></a>. </p> <p> Beachten Sie auch, dass Sie eine Option namens <code>"blocking"</code> übergeben: Sie müssen diese übergeben, wann immer Sie die Anfrage ändern möchten. Es bewirkt, dass die Listener-Funktion die Netzwerk-Anfrage blockiert, sodass der Browser wartet, bis der Listener eine Rückmeldung gibt, bevor er fortfährt. Weitere Informationen zu <code>"blocking"</code> finden Sie in der <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest"><code>webRequest.onBeforeRequest</code></a> Dokumentation. </p> <p>Um es zu testen, öffnen Sie eine Seite auf MDN, die Bilder enthält (zum Beispiel <a href="/de/docs/Mozilla/Add-ons/WebExtensions/user_interface">die Seite, die UI-Komponenten der Erweiterung auflistet</a>), <a href="https://extensionworkshop.com/documentation/develop/temporary-installation-in-firefox/#reloading_a_temporary_add-on" class="external" target="_blank">laden Sie die Erweiterung neu</a>, und laden Sie dann die MDN-Seite erneut. Sie sehen etwas wie dies:</p> <p> <img src="/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/beastify_by_redirect.png" alt="Images on a page replaced with a frog image" width="1944" height="1410" loading="lazy"> </p></div></section><section aria-labelledby="ändern_von_anfrage-headern"><h2 id="ändern_von_anfrage-headern"><a href="#ändern_von_anfrage-headern">Ändern von Anfrage-Headern</a></h2><div class="section-content"><p> Verwenden Sie abschließend <code>webRequest</code>, um Anfrage-Header zu ändern. In diesem Beispiel ändern Sie den "User-Agent" Header, sodass der Browser sich als Opera 12.16 identifiziert, aber nur, wenn Sie Seiten unter "<a href="https://useragentstring.com/" class="external" target="_blank">https://useragentstring.com/</a>" besuchen. </p> <p>Aktualisieren Sie die "manifest.json", um <code>https://useragentstring.com/</code> so einzuschließen:</p> <div class="code-example"><div class="example-header"><span class="language-name">json</span></div><pre class="brush: json notranslate"><code>{ "description": "Demonstrating webRequests", "manifest_version": 2, "name": "webRequest-demo", "version": "1.0", "permissions": [ "webRequest", "webRequestBlocking", "https://useragentstring.com/" ], "background": { "scripts": ["background.js"] } } </code></pre></div> <p>Ersetzen Sie "background.js" durch folgenden Code:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>let targetPage = "https://useragentstring.com/*"; let ua = "Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16"; function rewriteUserAgentHeader(e) { e.requestHeaders.forEach((header) => { if (header.name.toLowerCase() === "user-agent") { header.value = ua; } }); return { requestHeaders: e.requestHeaders }; } browser.webRequest.onBeforeSendHeaders.addListener( rewriteUserAgentHeader, { urls: [targetPage] }, ["blocking", "requestHeaders"], ); </code></pre></div> <p>Sie verwenden den <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders"><code>onBeforeSendHeaders</code></a> Event-Listener, um eine Funktion auszuführen, kurz bevor die Anfrage-Header gesendet werden.</p> <p> Die Listener-Funktion wird nur für Anfragen an URLs aufgerufen, die mit dem <code>targetPage</code> <a href="/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns">Muster</a> übereinstimmen. Beachten Sie auch, dass Sie erneut <code>"blocking"</code> als Option übergeben. Sie übergeben auch <code>"requestHeaders"</code>, was bedeutet, dass dem Listener ein Array übergeben wird, das die Anfrage-Header enthält, die Sie senden möchten. Weitere Informationen zu diesen Optionen finden Sie unter <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders"><code>webRequest.onBeforeSendHeaders</code></a>. </p> <p> Die Listener-Funktion sucht im Array der Anfrage-Header nach dem "User-Agent" Header, ersetzt dessen Wert mit dem Wert der <code>ua</code> Variable und gibt das modifizierte Array zurück. Dieses modifizierte Array wird an den Server gesendet. </p> <p> Um es zu testen, öffnen Sie <a href="https://useragentstring.com/" class="external" target="_blank">useragentstring.com</a> und überprüfen Sie, dass es den Browser als Firefox identifiziert. Laden Sie dann die Erweiterung neu, laden Sie <a href="https://useragentstring.com/" class="external" target="_blank">useragentstring.com</a> neu, und sehen Sie, dass Firefox nun als Opera identifiziert wird. </p> <p> <img src="/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/modified_request_header.png" alt="useragentstring.com showing details of the modified user agent string" width="1920" height="1080" loading="lazy"> </p></div></section><section aria-labelledby="mehr_erfahren"><h2 id="mehr_erfahren"><a href="#mehr_erfahren">Mehr erfahren</a></h2><div class="section-content"><p>Um mehr über alle Dinge zu erfahren, die Sie mit der <code>webRequest</code> API machen können, sehen Sie sich die <a href="/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest">Referenzdokumentation</a> an.</p></div></section></article><aside class="article-footer"><div class="article-footer-inner"><div class="svg-container"><svg xmlns="http://www.w3.org/2000/svg" width="162" height="162" 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Content available under <a href="/de/docs/MDN/Writing_guidelines/Attrib_copyright_license">a Creative Commons license</a>.</p></div></div></footer></div><script type="application/json" id="hydration">{"url":"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests","doc":{"isMarkdown":true,"isTranslated":true,"isActive":true,"flaws":{},"title":"HTTP-Anfragen abfangen","mdn_url":"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests","locale":"de","native":"Deutsch","sidebarHTML":"\n <ol>\n <li class=\"section\"><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions\">Browsererweiterungen</a></li>\n <li>\n <details>\n <summary>Erste Schritte</summary>\n <ol>\n <li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/What_are_WebExtensions\">Was sind Erweiterungen?</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Your_first_WebExtension\">Ihre erste Erweiterung</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension\">Ihre zweite Erweiterung</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Anatomy_of_a_WebExtension\">Anatomie einer Erweiterung</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Examples\">Beispielerweiterungen</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/What_next\">Was nun?</a></li>\n </ol>\n </details>\n </li>\n <li>\n <details>\n <summary>Konzepte</summary>\n <ol>\n <li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API\">JavaScript-APIs</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Content_scripts\">Content scripts</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Background_scripts\">Hintergrundskripte</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns\">Match patterns</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Working_with_files\">Arbeiten mit Dateien</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Internationalization\">Internationalisierung</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Content_Security_Policy\">Content Security Policy</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Native_messaging\">Native messaging</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Differences_between_API_implementations\">Unterschiede zwischen API-Implementierungen</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Chrome_incompatibilities\">Chrome-Inkompatibilitäten</a></li>\n </ol>\n </details>\n </li>\n <li>\n <details>\n <summary>Benutzeroberfläche</summary>\n <ol>\n <li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface\">Benutzeroberfläche</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Toolbar_button\">Toolbar-Button</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Page_actions\">Adressleisten-Schaltfläche</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Sidebars\">Seitenleisten</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Context_menu_items\">Kontextmenüelemente</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Options_pages\">Options page</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Extension_pages\">Erweiterungsseiten</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Notifications\">Notifications</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/Omnibox\">Address bar suggestions</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface/devtools_panels\">devtools panels</a></li>\n </ol>\n </details>\n </li>\n <li>\n <details open=\"\">\n <summary>Anleitungen</summary>\n <ol>\n <li><em><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests\" aria-current=\"page\">HTTP-Anfragen abfangen</a></em></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Modify_a_web_page\">Eine Webseite modifizieren</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Safely_inserting_external_content_into_a_page\">Externe Inhalte einfügen</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Sharing_objects_with_page_scripts\">Objekte mit Seitenskripts teilen</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Add_a_button_to_the_toolbar\">Einen Button zur Toolbar hinzufügen</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Implement_a_settings_page\">Implementieren einer Einstellungsseite</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Working_with_the_Tabs_API\">Arbeiten mit der Tabs-API</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_the_Bookmarks_API\">Arbeiten mit der Bookmarks API</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_the_Cookies_API\">Arbeiten mit der Cookies-API</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Work_with_contextual_identities\">Arbeiten mit kontextbezogenen Identitäten</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Interact_with_the_clipboard\">Interagieren mit der Zwischenablage</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Extending_the_developer_tools\">Erweiterung der Entwicklerwerkzeuge</a></li>\n<li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Build_a_cross_browser_extension\">Erstellen Sie eine plattformübergreifende Browser-Erweiterung</a></li>\n </ol>\n </details>\n </li>\n <li>\n <details>\n <summary>JavaScript-APIs</summary>\n <ol><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Browser_support_for_JavaScript_APIs\">Browser support for JavaScript APIs</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/action\">action</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/alarms\">alarms</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/bookmarks\">bookmarks</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/browserAction\">browserAction</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/browserSettings\">browserSettings</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/browsingData\">browsingData</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/captivePortal\">captivePortal</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/clipboard\">clipboard</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/commands\">commands</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/contentScripts\">contentScripts</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/contextualIdentities\">contextualIdentities</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/cookies\">cookies</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/declarativeNetRequest\">declarativeNetRequest</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/devtools\">devtools</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/dns\">dns</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/dom\">dom</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/downloads\">downloads</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/events\">events</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/extension\">extension</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/extensionTypes\">extensionTypes</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/find\">find</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/history\">history</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/i18n\">i18n</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/identity\">identity</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/idle\">idle</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/management\">management</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/menus\">menus</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/notifications\">notifications</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/omnibox\">omnibox</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/pageAction\">pageAction</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/permissions\">permissions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/pkcs11\">pkcs11</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/privacy\">privacy</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/proxy\">proxy</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/runtime\">runtime</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/scripting\">scripting</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/search\">search</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/sessions\">sessions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/sidebarAction\">sidebarAction</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/storage\">storage</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/tabs\">tabs</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/theme\">theme</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/topSites\">topSites</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/types\">types</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/userScripts\">userScripts</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webNavigation\">webNavigation</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest\">webRequest</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/windows\">windows</a></li></ol>\n </details>\n </li>\n <li>\n <details>\n <summary>Manifest-Schlüssel</summary>\n <ol>\n <li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json\">manifest.json</a></li>\n </ol>\n <ol><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/action\">action</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/author\">author</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/background\">background</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_action\">browser_action</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/browser_specific_settings\">browser_specific_settings</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/chrome_settings_overrides\">chrome_settings_overrides</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/chrome_url_overrides\">chrome_url_overrides</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/commands\">commands</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_scripts\">content_scripts</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_security_policy\">content_security_policy</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/declarative_net_request\">declarative_net_request</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/default_locale\">default_locale</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/description\">description</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/developer\">developer</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/devtools_page\">devtools_page</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/dictionaries\">dictionaries</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/externally_connectable\">externally_connectable</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/homepage_url\">homepage_url</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/host_permissions\">host_permissions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/icons\">icons</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/incognito\">incognito</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/manifest_version\">manifest_version</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/name\">name</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/offline_enabled\">offline_enabled</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/omnibox\">omnibox</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/optional_host_permissions\">optional_host_permissions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/optional_permissions\">optional_permissions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/options_page\">options_page</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/options_ui\">options_ui</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/page_action\">page_action</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions\">permissions</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/protocol_handlers\">protocol_handlers</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/short_name\">short_name</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/sidebar_action\">sidebar_action</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/storage\">storage</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme\">theme</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/theme_experiment\">theme_experiment</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/user_scripts\">user_scripts</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/version\">version</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/version_name\">version_name</a></li><li><a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/web_accessible_resources\">web_accessible_resources</a></li></ol>\n </details>\n </li>\n <li>\n <details>\n <summary>Erweiterungs-Workshop</summary>\n <ol>\n <li><a href=\"https://extensionworkshop.com/documentation/develop/\">Entwickeln</a></li>\n <li><a href=\"https://extensionworkshop.com/documentation/publish/\">Veröffentlichen</a></li>\n <li><a href=\"https://extensionworkshop.com/documentation/manage/\">Verwalten</a></li>\n <li><a href=\"https://extensionworkshop.com/documentation/enterprise/\">Unternehmen</a></li>\n </ol>\n </details>\n </li>\n <li class=\"section\"><a href=\"/de/docs/Mozilla/Add-ons/Contact_us\">Kontaktieren Sie uns</a></li>\n <li>\n <details>\n <summary>Kanäle</summary>\n <ol>\n <li><a href=\"https://blog.mozilla.org/addons\">Add-ons Blog</a></li>\n <li><a href=\"https://discourse.mozilla.org/c/add-ons\">Add-ons Forum</a></li>\n <li><a href=\"https://chat.mozilla.org/#/room/%23addons:mozilla.org\">Add-ons Chat</a></li>\n </ol>\n </details>\n </li>\n </ol>\n","sidebarMacro":"AddonSidebar","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<p>\n Um HTTP-Anfragen abzufangen, verwenden Sie die <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest\"><code>webRequest</code></a> API.\n Mit dieser API können Sie Listener für verschiedene Phasen einer HTTP-Anfrage hinzufügen.\n In den Listenern können Sie:\n</p>\n<ul>\n <li>Zugriff auf Anfrage- und Antwort-Header und -Körper erhalten.</li>\n <li>Anfragen abbrechen und umleiten.</li>\n <li>Anfrage- und Antwort-Header ändern.</li>\n</ul>\n<p>Dieser Artikel untersucht drei verschiedene Verwendungen des <code>webRequest</code> Moduls:</p>\n<ul>\n <li>Protokollieren von Anfrage-URLs, wenn sie gemacht werden.</li>\n <li>Umleiten von Anfragen.</li>\n <li>Ändern von Anfrage-Headern.</li>\n</ul>"}},{"type":"prose","value":{"id":"protokollieren_von_anfrage-urls","title":"Protokollieren von Anfrage-URLs","isH3":false,"content":"<p>\n Um zu sehen, wie Sie <code>webRequest</code> verwenden können, um Anfragen zu protokollieren, erstellen Sie ein neues Verzeichnis namens \"requests\".\n Erstellen Sie in diesem Verzeichnis eine Datei namens \"manifest.json\" und fügen Sie hinzu:\n</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">json</span></div><pre class=\"brush: json notranslate\"><code>{\n \"description\": \"Demonstrating webRequests\",\n \"manifest_version\": 2,\n \"name\": \"webRequest-demo\",\n \"version\": \"1.0\",\n\n \"permissions\": [\"webRequest\", \"<all_urls>\"],\n\n \"background\": {\n \"scripts\": [\"background.js\"]\n }\n}\n</code></pre></div>\n<p>Erstellen Sie als nächstes eine Datei namens \"background.js\" und fügen Sie hinzu:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>function logURL(requestDetails) {\n console.log(`Loading: ${requestDetails.url}`);\n}\n\nbrowser.webRequest.onBeforeRequest.addListener(logURL, {\n urls: [\"<all_urls>\"],\n});\n</code></pre></div>\n<p>\n Sie verwenden <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest\"><code>onBeforeRequest</code></a>, um die <code>logURL()</code> Funktion unmittelbar vor Beginn der Anfrage aufzurufen. Die <code>logURL()</code> Funktion erfasst die URL der Anfrage aus dem Ereignisobjekt und protokolliert sie in der Browser-Konsole.\n Das <code>{urls: [\"<all_urls>\"]}</code> <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns\">Muster</a> bedeutet, dass Sie HTTP-Anfragen an alle URLs abfangen.\n</p>\n<p>Um dies zu testen:</p>\n<ul>\n <li>\n <p><a href=\"https://extensionworkshop.com/documentation/develop/temporary-installation-in-firefox/\" class=\"external\" target=\"_blank\">Installieren Sie die Erweiterung</a></p>\n </li>\n <li>\n <p>Öffnen Sie die <a href=\"https://firefox-source-docs.mozilla.org/devtools-user/browser_console/\" class=\"external\" target=\"_blank\">Browser-Konsole</a> (verwenden Sie <kbd>Ctrl + Shift + J</kbd>)</p>\n </li>\n <li>\n <p>Aktivieren Sie <em>Show Content Messages</em> im Menü:</p>\n <p>\n <img src=\"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/browser_console_show_content_messages.png\" alt=\"Browser console menu: Show Content Messages\" width=\"456\" height=\"340\" loading=\"lazy\">\n </p>\n </li>\n <li>\n <p>Öffnen Sie einige Webseiten.</p>\n </li>\n</ul>\n<p>\n In der Browser-Konsole sollten Sie die URLs für Ressourcen sehen, die der Browser anfragt.\n Zum Beispiel zeigt dieser Screenshot die URLs vom Laden einer Wikipedia-Seite:\n</p>\n<p>\n <img src=\"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/browser_console_url_from_extension.png\" alt=\"Browser console menu: URLs from extension\" width=\"795\" height=\"480\" loading=\"lazy\">\n</p>\u003c!-- <iframe width=\"560\" height=\"315\" src=\"https://www.youtube-nocookie.com/embed/X3rMgkRkB1Q\" title=\"YouTube video\" allow=\"accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture\" allowfullscreen></iframe> -->"}},{"type":"prose","value":{"id":"umleiten_von_anfragen","title":"Umleiten von Anfragen","isH3":false,"content":"<p>Verwenden Sie nun <code>webRequest</code>, um HTTP-Anfragen umzuleiten. Ersetzen Sie zuerst \"manifest.json\" mit diesem:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">json</span></div><pre class=\"brush: json notranslate\"><code>{\n \"description\": \"Demonstrating webRequests\",\n \"manifest_version\": 2,\n \"name\": \"webRequest-demo\",\n \"version\": \"1.0\",\n\n \"permissions\": [\n \"webRequest\",\n \"webRequestBlocking\",\n \"https://developer.mozilla.org/\"\n ],\n\n \"background\": {\n \"scripts\": [\"background.js\"]\n }\n}\n</code></pre></div>\n<p>Die Änderungen hier:</p>\n<ul>\n <li>\n Fügen Sie die <code>webRequestBlocking</code> <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions\"><code>permission</code></a> hinzu.\n Diese zusätzliche Berechtigung wird benötigt, wenn eine Erweiterung eine Anfrage ändern möchte.\n </li>\n <li>Ersetzen Sie die <code><all_urls></code> Berechtigung durch einzelne <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions#host_permissions\">host permissions</a>, da es gute Praxis ist, die Anzahl der angeforderten Berechtigungen zu minimieren.</li>\n</ul>\n<p>Ersetzen Sie als nächstes \"background.js\" mit diesem:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>let pattern = \"https://developer.mozilla.org/*\";\nconst targetUrl =\n \"https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension/frog.jpg\";\n\nfunction redirect(requestDetails) {\n console.log(`Redirecting: ${requestDetails.url}`);\n if (requestDetails.url === targetUrl) {\n return;\n }\n return {\n redirectUrl: targetUrl,\n };\n}\n\nbrowser.webRequest.onBeforeRequest.addListener(\n redirect,\n { urls: [pattern], types: [\"image\"] },\n [\"blocking\"],\n);\n</code></pre></div>\n<p>\n Auch hier verwenden Sie den <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest\"><code>onBeforeRequest</code></a> Event-Listener, um eine Funktion unmittelbar vor jeder Anfrage auszuführen.\n Diese Funktion ersetzt die <code>redirectUrl</code> mit der Ziel-URL, die in der Funktion angegeben ist. In diesem Fall das Froschbild aus dem <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Your_second_WebExtension\">Tutorial für Ihre zweite Erweiterung</a>.\n</p>\n<p>\n Diesmal fangen Sie nicht jede Anfrage ab: die Option <code>{urls:[pattern], types:[\"image\"]}</code> gibt an, dass Sie nur Anfragen (1) an URLs unter \"<a href=\"/\">https://developer.mozilla.org/</a>\" und (2) für Bildressourcen abfangen.\n Weitere Informationen hierzu finden Sie unter <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/RequestFilter\"><code>webRequest.RequestFilter</code></a>.\n</p>\n<p>\n Beachten Sie auch, dass Sie eine Option namens <code>\"blocking\"</code> übergeben: Sie müssen diese übergeben, wann immer Sie die Anfrage ändern möchten.\n Es bewirkt, dass die Listener-Funktion die Netzwerk-Anfrage blockiert, sodass der Browser wartet, bis der Listener eine Rückmeldung gibt, bevor er fortfährt.\n Weitere Informationen zu <code>\"blocking\"</code> finden Sie in der <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeRequest\"><code>webRequest.onBeforeRequest</code></a> Dokumentation.\n</p>\n<p>Um es zu testen, öffnen Sie eine Seite auf MDN, die Bilder enthält (zum Beispiel <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/user_interface\">die Seite, die UI-Komponenten der Erweiterung auflistet</a>), <a href=\"https://extensionworkshop.com/documentation/develop/temporary-installation-in-firefox/#reloading_a_temporary_add-on\" class=\"external\" target=\"_blank\">laden Sie die Erweiterung neu</a>, und laden Sie dann die MDN-Seite erneut. Sie sehen etwas wie dies:</p>\n<p>\n <img src=\"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/beastify_by_redirect.png\" alt=\"Images on a page replaced with a frog image\" width=\"1944\" height=\"1410\" loading=\"lazy\">\n</p>"}},{"type":"prose","value":{"id":"ändern_von_anfrage-headern","title":"Ändern von Anfrage-Headern","isH3":false,"content":"<p>\n Verwenden Sie abschließend <code>webRequest</code>, um Anfrage-Header zu ändern.\n In diesem Beispiel ändern Sie den \"User-Agent\" Header, sodass der Browser sich als Opera 12.16 identifiziert, aber nur, wenn Sie Seiten unter \"<a href=\"https://useragentstring.com/\" class=\"external\" target=\"_blank\">https://useragentstring.com/</a>\" besuchen.\n</p>\n<p>Aktualisieren Sie die \"manifest.json\", um <code>https://useragentstring.com/</code> so einzuschließen:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">json</span></div><pre class=\"brush: json notranslate\"><code>{\n \"description\": \"Demonstrating webRequests\",\n \"manifest_version\": 2,\n \"name\": \"webRequest-demo\",\n \"version\": \"1.0\",\n\n \"permissions\": [\n \"webRequest\",\n \"webRequestBlocking\",\n \"https://useragentstring.com/\"\n ],\n\n \"background\": {\n \"scripts\": [\"background.js\"]\n }\n}\n</code></pre></div>\n<p>Ersetzen Sie \"background.js\" durch folgenden Code:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>let targetPage = \"https://useragentstring.com/*\";\n\nlet ua =\n \"Opera/9.80 (X11; Linux i686; Ubuntu/14.10) Presto/2.12.388 Version/12.16\";\n\nfunction rewriteUserAgentHeader(e) {\n e.requestHeaders.forEach((header) => {\n if (header.name.toLowerCase() === \"user-agent\") {\n header.value = ua;\n }\n });\n return { requestHeaders: e.requestHeaders };\n}\n\nbrowser.webRequest.onBeforeSendHeaders.addListener(\n rewriteUserAgentHeader,\n { urls: [targetPage] },\n [\"blocking\", \"requestHeaders\"],\n);\n</code></pre></div>\n<p>Sie verwenden den <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders\"><code>onBeforeSendHeaders</code></a> Event-Listener, um eine Funktion auszuführen, kurz bevor die Anfrage-Header gesendet werden.</p>\n<p>\n Die Listener-Funktion wird nur für Anfragen an URLs aufgerufen, die mit dem <code>targetPage</code> <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/Match_patterns\">Muster</a> übereinstimmen.\n Beachten Sie auch, dass Sie erneut <code>\"blocking\"</code> als Option übergeben. Sie übergeben auch <code>\"requestHeaders\"</code>, was bedeutet, dass dem Listener ein Array übergeben wird, das die Anfrage-Header enthält, die Sie senden möchten.\n Weitere Informationen zu diesen Optionen finden Sie unter <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest/onBeforeSendHeaders\"><code>webRequest.onBeforeSendHeaders</code></a>.\n</p>\n<p>\n Die Listener-Funktion sucht im Array der Anfrage-Header nach dem \"User-Agent\" Header, ersetzt dessen Wert mit dem Wert der <code>ua</code> Variable und gibt das modifizierte Array zurück.\n Dieses modifizierte Array wird an den Server gesendet.\n</p>\n<p>\n Um es zu testen, öffnen Sie <a href=\"https://useragentstring.com/\" class=\"external\" target=\"_blank\">useragentstring.com</a> und überprüfen Sie, dass es den Browser als Firefox identifiziert.\n Laden Sie dann die Erweiterung neu, laden Sie <a href=\"https://useragentstring.com/\" class=\"external\" target=\"_blank\">useragentstring.com</a> neu, und sehen Sie, dass Firefox nun als Opera identifiziert wird.\n</p>\n<p>\n <img src=\"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests/modified_request_header.png\" alt=\"useragentstring.com showing details of the modified user agent string\" width=\"1920\" height=\"1080\" loading=\"lazy\">\n</p>"}},{"type":"prose","value":{"id":"mehr_erfahren","title":"Mehr erfahren","isH3":false,"content":"<p>Um mehr über alle Dinge zu erfahren, die Sie mit der <code>webRequest</code> API machen können, sehen Sie sich die <a href=\"/de/docs/Mozilla/Add-ons/WebExtensions/API/webRequest\">Referenzdokumentation</a> an.</p>"}}],"toc":[{"text":"Protokollieren von Anfrage-URLs","id":"protokollieren_von_anfrage-urls"},{"text":"Umleiten von Anfragen","id":"umleiten_von_anfragen"},{"text":"Ändern von Anfrage-Headern","id":"ändern_von_anfrage-headern"},{"text":"Mehr erfahren","id":"mehr_erfahren"}],"summary":"Um HTTP-Anfragen abzufangen, verwenden Sie die webRequest API.\n Mit dieser API können Sie Listener für verschiedene Phasen einer HTTP-Anfrage hinzufügen.\n In den Listenern können Sie:","popularity":0,"modified":null,"other_translations":[{"locale":"en-US","title":"Intercept HTTP requests","native":"English (US)"},{"locale":"es","title":"Interceptar peticiones HTTP","native":"Español"},{"locale":"fr","title":"Intercepter les requêtes HTTP","native":"Français"},{"locale":"ja","title":"HTTP リクエストへの介入","native":"日本語"},{"locale":"pt-BR","title":"Interceptando requisições HTTP","native":"Português (do Brasil)"},{"locale":"ru","title":"Intercept HTTP requests","native":"Русский"},{"locale":"zh-CN","title":"拦截 HTTP 请求","native":"中文 (简体)"}],"pageType":"unknown","source":{"folder":"de/mozilla/add-ons/webextensions/intercept_http_requests","github_url":"https://github.com/mdn/translated-content/blob/main/files/de/mozilla/add-ons/webextensions/intercept_http_requests/index.md","last_commit_url":"https://github.com/mdn/translated-content/commit/null","filename":"index.md"},"short_title":"HTTP-Anfragen abfangen","parents":[{"uri":"/de/docs/Mozilla","title":"Mozilla"},{"uri":"/de/docs/Mozilla/Add-ons","title":"Add-ons"},{"uri":"/de/docs/Mozilla/Add-ons/WebExtensions","title":"Browsererweiterungen"},{"uri":"/de/docs/Mozilla/Add-ons/WebExtensions/Intercept_HTTP_requests","title":"HTTP-Anfragen abfangen"}],"pageTitle":"HTTP-Anfragen abfangen - Mozilla | MDN","noIndexing":false}}</script></body></html>