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()

8.4 動的マークアップの挿入

APIs for dynamically inserting markup into the document interact with the parser, and thus their behavior varies depending on whether they are used with HTML documents (and the HTML parser) or XML documents (and the XML parser).

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( )

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。

The resulting Document has an HTML parser associated with it, which can be given data to parse using document.write().

Documentがまだ解析されている場合、メソッドは効果がない。

Throws an "InvalidStateError" DOMException if the Document is an XML document.

Throws an "InvalidStateError" DOMException if the parser is currently executing a custom element constructor.

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

window.open()メソッドのように動作する。

Document objects have an ignore-opens-during-unload counter, which is used to prevent scripts from invoking the document.open() method (directly or indirectly) while the document is being unloaded. Initially, the counter must be set to zero.

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 responsible document specified by the entry settings object.

  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 ignore-opens-during-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 has a browsing context 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," before that issue is resolved.

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

  9. 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.

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

  11. 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.

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

  13. Set document to no-quirks mode.

  14. 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.

  15. Set the current document readiness of document to "loading".

  16. Finally, set the insertion point to point at just before the end of the input stream (which at this point will be empty).

  17. Return document.

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. heycam/webidl#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 "InvalidStateError" 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.open()メソッドによって開かれた入力ストリームを閉じる。

Throws an "InvalidStateError" DOMException if the Document is an XML document.

Throws an "InvalidStateError" DOMException if the parser is currently executing a custom element constructor.

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...)

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、パーサが実行されている間、HTMLパーサ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。Users agents are explicitly allowed to avoid executing script elements inserted via this method. And to make matters even worse, the exact behavior of this method can in some cases be dependent on network latency, which can lead to failures that are very hard to debug. For all these reasons, use of this method is strongly discouraged.

Throws an "InvalidStateError" DOMException when invoked on XML documents.

Throws an "InvalidStateError" DOMException if the parser is currently executing a custom element constructor.

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 the insertion point is undefined, then:

    1. If document's ignore-opens-during-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.

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

  5. 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 concatanation of all arguments passed.

8.4.4 document.writeln()

document . writeln(text...)

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。

Throws an "InvalidStateError" DOMException when invoked on XML documents.

Throws an "InvalidStateError" DOMException if the parser is currently executing a custom element constructor.

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