1. 8.4 動的マークアップの挿入
      1. 8.4.1 入力ストリームを開く
      2. 8.4.2 入力ストリームを閉じる
      3. 8.4.3 document.write()
      4. 8.4.4 document.writeln()
    2. 8.5 DOM解析

8.4 動的マークアップの挿入

マークアップを文書に動的に挿入するためのAPIはパーサーと相互作用するため、その動作は、HTML文書(およびHTMLパーサー)かXML文書(およびXMLパーサー)かのどちらで使用されるかによって異なる。

Document objects have a throw-on-dynamic-markup-insertion counter, which is used in conjunction with the create an element for the token algorithm to prevent custom element constructors from being able to use document.open(), document.close(), and document.write() when they are invoked by the parser. Initially, the counter must be set to zero.

8.4.1 入力ストリームを開く

document = document.open()

Document/open

Support in all current engines.

Firefox1+Safari11+Chrome64+
Opera51+Edge79+
Edge (Legacy)12+Internet Explorer4+
Firefox Android4+Safari iOS11+Chrome Android64+WebView Android64+Samsung Internet9.0+Opera Android47+

前のオブジェクトを再利用する場合を除き、あたかもそれが新しいDocumentオブジェクトであるかのように、Documentに正しい場所で置換され、その後返される。

結果として得られるDocumentはHTMLパーサーが関連付けられており、 document.write()を使用して解析するデータを与えることができる。

Documentがまだ解析されている場合、メソッドは効果がない。

DocumentXML文書である場合、"InvalidStateError" DOMExceptionを投げる。

パーサーがカスタム要素コンストラクターを現在実行している場合、"InvalidStateError" DOMExceptionを投げる。

window = document.open(url, name, features)

window.open()メソッドのように動作する。

Document objects have an active parser was aborted boolean, which is used to prevent scripts from invoking the document.open() and document.write() methods (directly or indirectly) after the document's active parser has been aborted. 最初はfalseである。

The document open steps, given a document, are as follows:

  1. If document is an XML document, then throw an "InvalidStateError" DOMException exception.

  2. If document's throw-on-dynamic-markup-insertion counter is greater than 0, then throw an "InvalidStateError" DOMException.

  3. Let entryDocument be the entry global object's associated Document.

  4. If document's origin is not same origin to entryDocument's origin, then throw a "SecurityError" DOMException.

  5. If document has an active parser whose script nesting level is greater than 0, then return document.

    This basically causes document.open() to be ignored when it's called in an inline script found during parsing, while still letting it have an effect when called from a non-parser task such as a timer callback or event handler.

  6. Similarly, if document's unload counter is greater than 0, then return document.

    This basically causes document.open() to be ignored when it's called from a beforeunload, pagehide, or unload event handler while the Document is being unloaded.

  7. If document's active parser was aborted is true, then return document.

    This notably causes document.open() to be ignored if it is called after a navigation has started, but only during the initial parse. See issue #4723 for more background.

  8. If document's browsing context is non-null and there is an existing attempt to navigate document's browsing context, then stop document loading given document.

    Issue #3447 looks into the distinction between an ongoing instance of the navigate algorithm versus tasks to navigate that are still queued. For the purpose of implementing this step, both an ongoing instance of the navigate algorithm and tasks queued to navigate should be counted towards "an existing attempt to navigate," at least until that issue is resolved.

  9. For each shadow-including inclusive descendant node of document, erase all event listeners and handlers given node.

  10. If document is the associated Document of document's relevant global object, then erase all event listeners and handlers given document's relevant global object.

  11. Replace all with null within document, without firing any mutation events.

  12. If document is fully active, then:

    1. Let newURL be a copy of entryDocument's URL.

    2. If entryDocument is not document, then set newURL's fragment to null.

    3. Run the URL and history update steps with document and newURL.

  13. Set document's is initial about:blank to false.

  14. If document's iframe load in progress flag is set, then set document's mute iframe load flag.

  15. Set document to no-quirks mode.

  16. Create a new HTML parser and associate it with document. This is a script-created parser (meaning that it can be closed by the document.open() and document.close() methods, and that the tokenizer will wait for an explicit call to document.close() before emitting an end-of-file token). The encoding confidence is irrelevant.

  17. Set the insertion point to point at just before the end of the input stream (which at this point will be empty).

  18. Update the current document readiness of document to "loading".

    This causes a readystatechange event to fire, but the event is actually unobservable to author code, because of the previous step which erased all event listeners and handlers that could observe it.

  19. documentを返す。

The document open steps do not affect whether a Document is ready for post-load tasks or completely loaded.

The open(unused1, unused2) method must return the result of running the document open steps with this Document object.

The unused1 and unused2 arguments are ignored, but kept in the IDL to allow code that calls the function with one or two arguments to continue working. They are necessary due to Web IDL overload resolution algorithm rules, which would throw a TypeError exception for such calls had the arguments not been there. whatwg/webidl issue #581 investigates changing the algorithm to allow for their removal. [WEBIDL]

The open(url, name, features) method must run these steps:

  1. If this Document object is not an active document, then throw an "InvalidAccessError" DOMException exception.

  2. Return the result of running the window open steps with url, name, and features.

8.4.2 入力ストリームを閉じる

document.close()

Document/close

Support in all current engines.

Firefox1+Safari11+Chrome64+
Opera51+Edge79+
Edge (Legacy)12+Internet Explorer4+
Firefox Android4+Safari iOS11+Chrome Android64+WebView Android64+Samsung Internet9.0+Opera Android47+

document.open()メソッドによって開かれた入力ストリームを閉じる。

DocumentXML文書である場合、"InvalidStateError" DOMExceptionを投げる。

パーサーがカスタム要素コンストラクターを現在実行している場合、"InvalidStateError" DOMExceptionを投げる。

The close() method must run the following steps:

  1. If the Document object is an XML document, then throw an "InvalidStateError" DOMException.

  2. If the Document object's throw-on-dynamic-markup-insertion counter is greater than zero, then throw an "InvalidStateError" DOMException.

  3. If there is no script-created parser associated with the document, then return.

  4. Insert an explicit "EOF" character at the end of the parser's input stream.

  5. If there is a pending parsing-blocking script, then return.

  6. Run the tokenizer, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the explicit "EOF" character or spins the event loop.

8.4.3 document.write()

document.write(...text)

Document/write

Support in all current engines.

Firefox1+Safari1+Chrome1+
Opera3+Edge79+
Edge (Legacy)12+Internet Explorer4+
Firefox Android4+Safari iOS1+Chrome Android18+WebView Android1+Samsung Internet1.0+Opera Android10.1+

一般に、与えられた文字列をDocumentの入力ストリームに加える。

このメソッドは非常に特異な振る舞いを持つ。一部の場合において、このメソッドは、パーサーが実行されている間、HTMLパーサーの状態に影響を与えることができる。その結果、文書のソースに対応しないDOMをもたらす(たとえば、記述された文字列が、文字列"<plaintext>"または"<!--"である場合)。他の例では、あたかもdocument.open()が呼び出されていたかのように、呼び出しが最初に現在のページをクリアできる。さらに多くの例では、メソッドは単に無視されるか、または例外を投げる。ユーザーエージェントは、このメソッドを介して挿入されたscript要素の実行を回避することを明示的に許可される。さらに悪いことに、このメソッドの正確な動作は、場合によってはネットワーク遅延に依存する可能性があり、これはデバッグが非常に困難な障害につながる可能性がある。これらすべての理由から、このメソッドの使用は強く勧めない。

XML文書で呼び出されるとき、"InvalidStateError" DOMExceptionを投げる。

パーサーがカスタム要素コンストラクターを現在実行している場合、"InvalidStateError" DOMExceptionを投げる。

Document objects have an ignore-destructive-writes counter, which is used in conjunction with the processing of script elements to prevent external scripts from being able to use document.write() to blow away the document by implicitly calling document.open(). Initially, the counter must be set to zero.

The document write steps, given a Document object document and a string input, are as follows:

  1. If document is an XML document, then throw an "InvalidStateError" DOMException.

  2. If document's throw-on-dynamic-markup-insertion counter is greater than 0, then throw an "InvalidStateError" DOMException.

  3. If document's active parser was aborted is true, then return.

  4. If the insertion point is undefined, then:

    1. If document's unload counter is greater than 0 or document's ignore-destructive-writes counter is greater than 0, then return.

    2. Run the document open steps with document.

  5. Insert input into the input stream just before the insertion point.

  6. If there is no pending parsing-blocking script, have the HTML parser process input, one code point at a time, processing resulting tokens as they are emitted, and stopping when the tokenizer reaches the insertion point or when the processing of the tokenizer is aborted by the tree construction stage (this can happen if a script end tag token is emitted by the tokenizer).

    If the document.write() method was called from script executing inline (i.e. executing because the parser parsed a set of script tags), then this is a reentrant invocation of the parser. If the parser pause flag is set, the tokenizer will abort immediately and no HTML will be parsed, per the tokenizer's parser pause flag check.

The document.write(...) method, when invoked, must run the document write steps with this Document object and a string that is the concatenation of all arguments passed.

8.4.4 document.writeln()

document.writeln(...text)

Document/writeln

Support in all current engines.

Firefox1+Safari11+Chrome64+
Opera51+Edge79+
Edge (Legacy)12+Internet Explorer4+
Firefox Android4+Safari iOS11+Chrome Android64+WebView Android64+Samsung Internet9.0+Opera Android47+

改行文字の後に、与えられた文字列をDocumentの入力ストリームに加える。必要ならば、open()メソッドを暗黙のうちに最初に呼び出す。

XML文書で呼び出されるとき、"InvalidStateError" DOMExceptionを投げる。

パーサーがカスタム要素コンストラクターを現在実行している場合、"InvalidStateError" DOMExceptionを投げる。

The document.writeln(...) method, when invoked, must run the document write steps with this Document object and a string that is the concatenation of all arguments passed and U+000A LINE FEED.

8.5 DOM解析

DOMParser

Support in all current engines.

Firefox1+Safari1.3+Chrome1+
Opera8+Edge79+
Edge (Legacy)12+Internet Explorer9+
Firefox Android4+Safari iOS1+Chrome Android18+WebView Android1+Samsung Internet1.0+Opera Android10.1+

The DOMParser interface allows authors to create new Document objects by parsing strings, as either HTML or XML.

parser = new DOMParser()

DOMParser/DOMParser

Support in all current engines.

Firefox1+Safari1.3+Chrome1+
Opera8+Edge79+
Edge (Legacy)12+Internet Explorer9+
Firefox Android4+Safari iOS1+Chrome Android18+WebView Android1+Samsung Internet1.0+Opera AndroidYes

Constructs a new DOMParser object.

document = parser.parseFromString(string, type)

DOMParser/parseFromString

Support in all current engines.

Firefox1+Safari1.3+Chrome1+
Opera8+Edge79+
Edge (Legacy)12+Internet Explorer9+
Firefox Android4+Safari iOS1+Chrome AndroidYesWebView Android1+Samsung InternetYesOpera AndroidYes

Parses string using either the HTML or XML parser, according to type, and returns the resulting Document. type can be "text/html" (which will invoke the HTML parser), or any of "text/xml", "application/xml", "application/xhtml+xml", or "image/svg+xml" (which will invoke the XML parser).

For the XML parser, if string cannot be parsed, then the returned Document will contain elements describing the resulting error.

script 要素は解析中に評価されず、結果の文書のエンコーディングは常にUTF-8となることに注意する。

typeに上記以外の値を指定すると、TypeError例外が投げられる。

The design of DOMParser, as a class that needs to be constructed and then have its parseFromString() method called, is an unfortunate historical artifact. もし今日にこの機能を設計していたとしたら、それはスタンドアロン機能になっただろう。

[Exposed=Window]
interface DOMParser {
  constructor();

  [NewObject] Document parseFromString(DOMString string, DOMParserSupportedType type);
};

enum DOMParserSupportedType {
  "text/html",
  "text/xml",
  "application/xml",
  "application/xhtml+xml",
  "image/svg+xml"
};

The new DOMParser() constructor steps are to do nothing.

The parseFromString(string, type) method steps are:

  1. Let document be a new Document, whose content type is type and url is this's relevant global object's associated Document's URL.

    The document's encoding will be left as its default, of UTF-8. In particular, any XML declarations or meta elements found while parsing string will have no effect.

  2. Switch on type:

    "text/html"
    1. Set document's type to "html".

    2. Create an HTML parser parser, associated with document.

    3. Place string into the input stream for parser. The encoding confidence is irrelevant.

    4. Start parser and let it run until it has consumed all the characters just inserted into the input stream.

      This might mutate the document's mode.

    Since document does not have a browsing context, scripting is disabled.

    Otherwise
    1. Create an XML parser parse, associated with document, and with XML scripting support disabled.

    2. Parse string using parser.

    3. If the previous step resulted in an XML well-formedness or XML namespace well-formedness error, then:

      1. Assert: document has no child nodes.

      2. Let root be the result of creating an element given document, "parsererror", and "http://www.mozilla.org/newlayout/xml/parsererror.xml".

      3. Optionally, add attributes or children to root to describe the nature of the parsing error.

      4. Append root to document.

  3. documentを返す。