HTML
Living Standard — Last Updated 25 July 2025
Living Standard — Last Updated 25 July 2025
NavigatorオブジェクトSupport in all current engines.
Navigatorのインスタンスは、ユーザーエージェント（クライアント）のIDと状態を表す。これはまた、さまざまなAPIが配置される汎用グローバルとしても使用されているが、これは構築の前例ではない。代わりに、WindowOrWorkerGlobalScopeミックスインまたは同等のものを使用する。
[Exposed =Window ]
interface Navigator {
// objects implementing this interface also implement the interfaces given below
};
Navigator includes NavigatorID ;
Navigator includes NavigatorLanguage ;
Navigator includes NavigatorOnLine ;
Navigator includes NavigatorContentUtils ;
Navigator includes NavigatorCookies ;
Navigator includes NavigatorPlugins ;
Navigator includes NavigatorConcurrentHardware ;These interface mixins are defined separately so that WorkerNavigator can reuse parts of the Navigator interface.
Each Window has an associated Navigator, which is a Navigator object. Upon creation of the Window object, its associated Navigator must be set to a new Navigator object created in the Window object's relevant realm.
Support in all current engines.
The navigator and clientInformation getter steps are to return this's associated Navigator.
interface mixin NavigatorID {
readonly attribute DOMString appCodeName ; // constant "Mozilla"
readonly attribute DOMString appName ; // constant "Netscape"
readonly attribute DOMString appVersion ;
readonly attribute DOMString platform ;
readonly attribute DOMString product ; // constant "Gecko"
[Exposed =Window ] readonly attribute DOMString productSub ;
readonly attribute DOMString userAgent ;
[Exposed =Window ] readonly attribute DOMString vendor ;
[Exposed =Window ] readonly attribute DOMString vendorSub ; // constant ""
};特定の場合において、業界全体の最善の努力にもかかわらず、ウェブブラウザーは、ウェブ著者が回避することを余儀なくされるバグや限界がある。
このセクションは、スクリプトから使用中のユーザーエージェントの種類を判断するために使用できる属性の集合を定義し、順番にこれらの問題を回避する。
The user agent has a navigator compatibility mode, which is either Chrome, Gecko, or WebKit.
The navigator compatibility mode constrains the NavigatorID mixin to the combinations of attribute values and presence of taintEnabled() and oscpu that are known to be compatible with existing web content.
クライアント検出は常に既知の現行バージョンの検出に限定されるべきである。将来のバージョンおよび未知のバージョンは、常に完全に準拠するよう仮定されるべきである。
self.navigator.appCodeName文字列"Mozilla"を返す。
self.navigator.appName文字列"Netscape"を返す。
self.navigator.appVersionブラウザーのバージョンを返す。
self.navigator.platformプラットフォームの名前を返す。
self.navigator.product文字列"Gecko"を返す。
window.navigator.productSub文字列"20030107"または文字列"20100101"のいずれかを返す。
self.navigator.userAgentSupport in all current engines.
Support in all current engines.
完全な`User-Agent`ヘッダーを返す。
window.navigator.vendor空文字列、文字列"Apple Computer, Inc."、または文字列"Google Inc."のいずれかを返す。
window.navigator.vendorSub空文字列を返す。
The appCodeName getter steps are to return "Mozilla".
The appName getter steps are to return "Netscape".
The appVersion getter steps are to return the appropriate string that starts with "5.0 (", as follows:
User-Agent` value that follows the "Mozilla/" prefix.Return trail.
If trail starts with "5.0 (Windows", then return "5.0 (Windows)".
Otherwise, return the prefix of trail up to but not including the first U+003B (;), concatenated with the character U+0029 RIGHT PARENTHESIS. For example, "5.0 (Macintosh)", "5.0 (Android 10)", or "5.0 (X11)".
The platform getter steps are to return a string representing the platform on which the browser is executing (e.g. "MacIntel", "Win32", "Linux x86_64", "Linux armv81") or, for privacy and compatibility, a string that is commonly returned on another platform.
The product getter steps are to return "Gecko".
The productSub getter steps are to return the appropriate string from the following list:
The string "20030107".
The string "20100101".
The userAgent getter steps are to return the default `User-Agent` value.
The vendor getter steps are to return the appropriate string from the following list:
The string "Google Inc.".
The empty string.
The string "Apple Computer, Inc.".
The vendorSub getter steps are to return the empty string.
If the navigator compatibility mode is Gecko, then the user agent must also support the following partial interface:
partial interface mixin NavigatorID {
[Exposed =Window ] boolean taintEnabled (); // constant false
[Exposed =Window ] readonly attribute DOMString oscpu ;
};The taintEnabled() method must return false.
The oscpu attribute's getter must return either the empty string or a string representing the platform on which the browser is executing, e.g. "Windows NT 10.0; Win64; x64", "Linux x86_64".
Any information in this API that varies from user to user can be used to profile the user. In fact, if enough such information is available, a user can actually be uniquely identified. For this reason, user agent implementers are strongly urged to include as little information in this API as possible.
interface mixin NavigatorLanguage {
readonly attribute DOMString language ;
readonly attribute FrozenArray <DOMString > languages ;
};self.navigator.languageSupport in all current engines.
Support in all current engines.
ユーザーの優先言語を表す言語タグを返す。
self.navigator.languagesSupport in all current engines.
Support in all current engines.
ユーザーの優先言語を表す言語タグの配列を返す。
最も優先される言語は、navigator.languageによって返されるものである。
どのユーザーの優先言語かユーザーエージェントの理解が変更する場合、languagechangeイベントは、WindowまたはWorkerGlobalScopeオブジェクトで発火する。
The language getter steps are to return a valid BCP 47 language tag representing either a plausible language or the user's most preferred language. [BCP47]
The languages getter steps are to return a frozen array of valid BCP 47 language tags representing either one or more plausible languages, or the user's preferred languages, ordered by preference with the most preferred language first. The same object must be returned until the user agent needs to return different values, or values in a different order. [BCP47]
Whenever the user agent needs to make the navigator.languages attribute of a Window or WorkerGlobalScope object global return a new set of language tags, the user agent must queue a global task on the DOM manipulation task source given global to fire an event named languagechange at global, and wait until that task begins to be executed before actually returning a new value.
To determine a plausible language, the user agent should bear in mind the following:
Any information in this API that varies from user to user can be used to profile or identify the user.en-US" is suggested; if all users of the service use that same value, that reduces the possibility of distinguishing the users from each other. To avoid introducing any more fingerprinting vectors, user agents should use the same list for the APIs defined in this function as for the HTTP `Accept-Language` header.
interface mixin NavigatorOnLine {
readonly attribute boolean onLine ;
};self.navigator.onLineSupport in all current engines.
Support in all current engines.
ユーザーエージェントが正確にオフラインである（ネットワークから切断されている）場合にfalseを返すユーザーエージェントがオンラインかもしれない場合にtrueを返す。
The onLine attribute must return false if the user agent will not contact the network when the user follows links or when a script requests a remote page (or knows that such an attempt would fail), and must return true otherwise.
When the value that would be returned by the navigator.onLine attribute of a Window or WorkerGlobalScope global changes from true to false, the user agent must queue a global task on the networking task source given global to fire an event named offline at global.
On the other hand, when the value that would be returned by the navigator.onLine attribute of a Window or WorkerGlobalScope global changes from false to true, the user agent must queue a global task on the networking task source given global to fire an event named online at the Window or WorkerGlobalScope object.
この属性は、本質的に信頼できない。コンピューターは、インターネット接続がなくてもネットワークに接続できる。
この例において、ブラウザーがオンラインおよびオフラインになるように、インジケーターが更新される。
<!DOCTYPE HTML>
< html lang = "en" >
< head >
< title > Online status</ title >
< script >
function updateIndicator() {
document. getElementById( 'indicator' ). textContent = navigator. onLine ? 'online' : 'offline' ;
}
</ script >
</ head >
< body onload = "updateIndicator()" ononline = "updateIndicator()" onoffline = "updateIndicator()" >
< p > The network is: < span id = "indicator" > (state unknown)</ span >
</ body >
</ html > registerProtocolHandler()メソッドNavigator/registerProtocolHandler
interface mixin NavigatorContentUtils {
[SecureContext ] undefined registerProtocolHandler (DOMString scheme , USVString url );
[SecureContext ] undefined unregisterProtocolHandler (DOMString scheme , USVString url );
};window.navigator.registerProtocolHandler(scheme, url)schemeのハンドラーをurlに登録する。たとえば、オンライン電話メッセージングサービスは、それ自体をsms:スキームのハンドラーとして登録できるため、ユーザーがそのようなリンクをクリックする場合に、そのウェブサイトを使用する機会が与えられる。[SMS]
url内文字列"%s"は、扱うにあたりコンテンツのURLをどこに置くかのプレースホルダーとして使用される。
ユーザーエージェントが登録をブロックする場合、"SecurityError" DOMExceptionを投げる（これは、たとえば"http"のハンドラーとして登録しようとした場合に発生する可能性がある）。
"%s"文字列がurlにない場合、"SyntaxError" DOMExceptionを投げる。
window.navigator.unregisterProtocolHandler(scheme, url)Navigator/unregisterProtocolHandler
Support in one engine only.
引数で指定されたハンドラーの登録を解除する。
ユーザーエージェントが登録解除をブロックする場合、"SecurityError" DOMExceptionを投げる（これは、たとえば、不正なスキームの場合に発生する可能性がある）。
"%s"文字列がurlにない場合、"SyntaxError" DOMExceptionを投げる。
The registerProtocolHandler(scheme, url) method steps are:
Let (normalizedScheme, normalizedURLString) be the result of running normalize protocol handler parameters with scheme, url, and this's relevant settings object.
In parallel: register a protocol handler for normalizedScheme and normalizedURLString. User agents may, within the constraints described, do whatever they like. A user agent could, for instance, prompt the user and offer the user the opportunity to add the site to a shortlist of handlers, or make the handlers their default, or cancel the request. User agents could also silently collect the information, providing it only when relevant to the user.
User agents should keep track of which sites have registered handlers (even if the user has declined such registrations) so that the user is not repeatedly prompted with the same request.
If the registerProtocolHandler() automation mode of this's relevant global object's associated Document is not "none", the user agent should first verify that it is in an automation context (see WebDriver's security considerations). The user agent should then bypass the above communication of information and gathering of user consent, and instead do the following based on the value of the registerProtocolHandler() automation mode:
autoAccept"Act as if the user has seen the registration details and accepted the request.
autoReject"Act as if the user has seen the registration details and rejected the request.
When the user agent uses this handler for a URL inputURL:
Set the username given inputURL and the empty string.
Set the password given inputURL and the empty string.
Let inputURLString be the serialization of inputURL.
Let encodedURL be the result of running UTF-8 percent-encode on inputURLString using the component percent-encode set.
Let handlerURLString be normalizedURLString.
Replace the first instance of "%s" in handlerURLString with encodedURL.
Let resultURL be the result of parsing handlerURLString.
If the user had visited a site at https://example.com/ that made the following call:
navigator. registerProtocolHandler( 'web+soup' , 'soup?url=%s' ) ...and then, much later, while visiting https://www.example.net/, clicked on a link such as:
< a href = "web+soup:chicken-kïwi" > Download our Chicken Kïwi soup!</ a > ...then the UA might navigate to the following URL:
https://example.com/soup?url=web+soup:chicken-k%C3%AFwi
This site could then do whatever it is that it does with soup (synthesize it and ship it to the user, or whatever).
This does not define when the handler is used. To some extent, the processing model for navigating across documents defines some cases where it is relevant, but in general user agents may use this information wherever they would otherwise consider handing schemes to native plugins or helper applications.
The unregisterProtocolHandler(scheme, url) method steps are:
Let (normalizedScheme, normalizedURLString) be the result of running normalize protocol handler parameters with scheme, url, and this's relevant settings object.
In parallel: unregister the handler described by normalizedScheme and normalizedURLString.
To normalize protocol handler parameters, given a string scheme, a string url, and an environment settings object environment, run these steps:
Set scheme to scheme, converted to ASCII lowercase.
If scheme is neither a safelisted scheme nor a string starting with "web+" followed by one or more ASCII lower alphas, then throw a "SecurityError" DOMException.
This means that including a colon in scheme (as in "mailto:") will throw.
The following schemes are the safelisted schemes:
bitcoinftpftpsgeoimircircsmagnetmailtomatrixmmsnewsnntpopenpgp4fprsftpsipsmssmstosshtelurnwebcalwtaixmppThis list can be changed. If there are schemes that ought to be added, please send feedback.
If url does not contain "%s", then throw a "SyntaxError" DOMException.
Let urlRecord be the result of encoding-parsing a URL given url, relative to environment.
If urlRecord is failure, then throw a "SyntaxError" DOMException.
This is forcibly the case if the %s placeholder is in the host or port of the URL.
If urlRecord's scheme is not an HTTP(S) scheme or urlRecord's origin is not same origin with environment's origin, then throw a "SecurityError" DOMException.
Assert: the result of Is url potentially trustworthy? given urlRecord is "Potentially Trustworthy".
Because normalize protocol handler parameters is run within a secure context, this is implied by the same origin condition.
Return (scheme, urlRecord).
The serialization of urlRecord will by definition not be a valid URL string as it includes the string "%s" which is not a valid component in a URL.
Custom scheme handlers can introduce a number of concerns, in particular privacy concerns.
Hijacking all web usage. User agents should not allow schemes that are key to its normal operation, such as an HTTP(S) scheme, to be rerouted through third-party sites. This would allow a user's activities to be trivially tracked, and would allow user information, even in secure connections, to be collected.
Hijacking defaults. User agents are strongly urged to not automatically change any defaults, as this could lead the user to send data to remote hosts that the user is not expecting. New handlers registering themselves should never automatically cause those sites to be used.
Registration spamming. User agents should consider the possibility that a site will attempt to register a large number of handlers, possibly from multiple domains (e.g., by redirecting through a series of pages each on a different domain, and each registering a handler for web+spam: — analogous practices abusing other web browser features have been used by pornography web sites for many years). User agents should gracefully handle such hostile attempts, protecting the user.
Hostile handler metadata. User agents should protect against typical attacks against strings embedded in their interface, for example ensuring that markup or escape characters in such strings are not executed, that null bytes are properly handled, that over-long strings do not cause crashes or buffer overruns, and so forth.
Leaking private data. Web page authors may reference a custom scheme handler using URL data considered private. They might do so with the expectation that the user's choice of handler points to a page inside the organization, ensuring that sensitive data will not be exposed to third parties. However, a user may have registered a handler pointing to an external site, resulting in a data leak to that third party. Implementers might wish to consider allowing administrators to disable custom handlers on certain subdomains, content types, or schemes.
Interface interference. User agents should be prepared to handle intentionally long arguments to the methods. For example, if the user interface exposed consists of an "accept" button and a "deny" button, with the "accept" binding containing the name of the handler, it's important that a long name not cause the "deny" button to be pushed off the screen.
Each Document has a registerProtocolHandler() automation mode. It defaults to "none", but it also can be either "autoAccept" or "autoReject".
For the purposes of user agent automation and website testing, this standard defines Set RPH Registration Mode WebDriver extension command. It instructs the user agent to place a Document into a mode where it will automatically simulate a user either accepting or rejecting and registration confirmation prompt dialog.
| HTTP Method | URI Template |
|---|---|
`POST` | /session/{session id}/custom-handlers/set-mode |
The remote end steps are:
If parameters is not a JSON Object, return a WebDriver error with WebDriver error code invalid argument.
Let mode be the result of getting a property named "mode" from parameters.
If mode is not "autoAccept", "autoReject", or "none", return a WebDriver error with WebDriver error code invalid argument.
Let document be the current browsing context's active document.
Set document's registerProtocolHandler() automation mode to mode.
Return success with data null.
interface mixin NavigatorCookies {
readonly attribute boolean cookieEnabled ;
};window.navigator.cookieEnabledSupport in all current engines.
クッキーの設定が拒否される場合falseを返し、そうでなければtrueを返す。
The cookieEnabled attribute must return true if the user agent attempts to handle cookies according to HTTP State Management Mechanism, and false if it ignores cookie change requests. [COOKIES]
window.navigator.pdfViewerEnabledユーザーエージェントがPDFファイルにナビゲートするときにPDFファイルのインライン表示をサポートしている場合はtrueを返し、そうでなければfalseを返す。後者の場合、PDFファイルは外部ソフトウェアによって処理される。
interface mixin NavigatorPlugins {
[SameObject ] readonly attribute PluginArray plugins ;
[SameObject ] readonly attribute MimeTypeArray mimeTypes ;
boolean javaEnabled ();
readonly attribute boolean pdfViewerEnabled ;
};
[Exposed =Window ,
LegacyUnenumerableNamedProperties ]
interface PluginArray {
undefined refresh ();
readonly attribute unsigned long length ;
getter Plugin ? item (unsigned long index );
getter Plugin ? namedItem (DOMString name );
};
[Exposed =Window ,
LegacyUnenumerableNamedProperties ]
interface MimeTypeArray {
readonly attribute unsigned long length ;
getter MimeType ? item (unsigned long index );
getter MimeType ? namedItem (DOMString name );
};
[Exposed =Window ,
LegacyUnenumerableNamedProperties ]
interface Plugin {
readonly attribute DOMString name ;
readonly attribute DOMString description ;
readonly attribute DOMString filename ;
readonly attribute unsigned long length ;
getter MimeType ? item (unsigned long index );
getter MimeType ? namedItem (DOMString name );
};
[Exposed =Window ]
interface MimeType {
readonly attribute DOMString type ;
readonly attribute DOMString description ;
readonly attribute DOMString suffixes ;
readonly attribute Plugin enabledPlugin ;
};Although these days detecting PDF viewer support can be done via navigator.pdfViewerEnabled, for historical reasons, there are a number of complex and intertwined interfaces that provide the same capability, which legacy code relies on. This section specifies both the simple modern variant and the complicated historical one.
Each user agent has a PDF viewer supported boolean, whose value is implementation-defined (and might vary according to user preferences).
This value also impacts the navigation processing model.
Each Window object has a PDF viewer plugin objects list. If the user agent's PDF viewer supported is false, then it is the empty list. Otherwise, it is a list containing five Plugin objects, whose names are, respectively:
PDF Viewer"Chrome PDF Viewer"Chromium PDF Viewer"Microsoft Edge PDF Viewer"WebKit built-in PDF"The values of the above list form the PDF viewer plugin names list.
These names were chosen based on evidence of what websites historically search for, and thus what is necessary for user agents to expose in order to maintain compatibility with existing content. They are ordered alphabetically. The "PDF Viewer" name was then inserted in the 0th position so that the enabledPlugin getter could point to a generic plugin name.
Each Window object has a PDF viewer mime type objects list. If the user agent's PDF viewer supported is false, then it is the empty list. Otherwise, it is a list containing two MimeType objects, whose types are, respectively:
application/pdf"text/pdf"The values of the above list form the PDF viewer mime types list.
Each NavigatorPlugins object has a plugins array, which is a new PluginArray, and a mime types array, which is a new MimeTypeArray.
The NavigatorPlugins mixin's plugins getter steps are to return this's plugins array.
The NavigatorPlugins mixin's mimeTypes getter steps are to return this's mime types array.
The NavigatorPlugins mixin's javaEnabled() method steps are to return false.
Support in all current engines.
The NavigatorPlugins mixin's pdfViewerEnabled getter steps are to return the user agent's PDF viewer supported.
The PluginArray interface supports named properties. If the user agent's PDF viewer supported is true, then they are the PDF viewer plugin names. Otherwise, they are the empty list.
The PluginArray interface's namedItem(name) method steps are:
For each Plugin plugin of this's relevant global object's PDF viewer plugin objects: if plugin's name is name, then return plugin.
Return null.
The PluginArray interface supports indexed properties. The supported property indices are the indices of this's relevant global object's PDF viewer plugin objects.
The PluginArray interface's item(index) method steps are:
Let plugins be this's relevant global object's PDF viewer plugin objects.
If index < plugins's size, then return plugins[index].
Return null.
The PluginArray interface's length getter steps are to return this's relevant global object's PDF viewer plugin objects's size.
The PluginArray interface's refresh() method steps are to do nothing.
The MimeTypeArray interface supports named properties. If the user agent's PDF viewer supported is true, then they are the PDF viewer mime types. Otherwise, they are the empty list.
The MimeTypeArray interface's namedItem(name) method steps are:
For each MimeType mimeType of this's relevant global object's PDF viewer mime type objects: if mimeType's type is name, then return mimeType.
Return null.
The MimeTypeArray interface supports indexed properties. The supported property indices are the indices of this's relevant global object's PDF viewer mime type objects.
The MimeTypeArray interface's item(index) method steps are:
Let mimeTypes be this's relevant global object's PDF viewer mime type objects.
If index < mimeTypes's size, then return mimeTypes[index].
Return null.
The MimeTypeArray interface's length getter steps are to return this's relevant global object's PDF viewer mime type objects's size.
Each Plugin object has a name, which is set when the object is created.
The Plugin interface's name getter steps are to return this's name.
The Plugin interface's description getter steps are to return "Portable Document Format".
The Plugin interface's filename getter steps are to return "internal-pdf-viewer".
The Plugin interface supports named properties. If the user agent's PDF viewer supported is true, then they are the PDF viewer mime types. Otherwise, they are the empty list.
The Plugin interface's namedItem(name) method steps are:
For each MimeType mimeType of this's relevant global object's PDF viewer mime type objects: if mimeType's type is name, then return mimeType.
Return null.
The Plugin interface supports indexed properties. The supported property indices are the indices of this's relevant global object's PDF viewer mime type objects.
The Plugin interface's item(index) method steps are:
Let mimeTypes be this's relevant global object's PDF viewer mime type objects.
If index < mimeTypes's size, then return mimeTypes[index].
Return null.
The Plugin interface's length getter steps are to return this's relevant global object's PDF viewer mime type objects's size.
Each MimeType object has a type, which is set when the object is created.
The MimeType interface's type getter steps are to return this's type.
The MimeType interface's description getter steps are to return "Portable Document Format".
The MimeType interface's suffixes getter steps are to return "pdf".
The MimeType interface's enabledPlugin getter steps are to return this's relevant global object's PDF viewer plugin objects[0] (i.e., the generic "PDF Viewer" one).