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DocumentType: before() メソッド - Web API | MDN
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DocumentType: before() メソッド
Baseline
Widely available
This feature is well established and works across many devices and browser versions. It’s been available across browsers since 2018年4月.
The DocumentType.before() 一連の Node オブジェクトまたは文字列を、この DocumentType の親ノードの子リストの、この DocumentType の直前に挿入します。文字列は等価な Text ノードとして挿入されます。
構文
js
before(param1)
before(param1, param2)
before(param1, param2, /* … ,*/ paramN)
引数
param1, …,paramN-
挿入する一連の
Nodeオブジェクト、または文字列です。
返値
なし (undefined)。
例外
HierarchyRequestErrorDOMException-
ノードが階層内の指定の位置に挿入できなかった場合に発生します。
例
条件付きコメントの追加
コメントノードは doctype 宣言の前でも有効ですが、 IE で互換モードになることを考えるとお勧めできません。条件付きコメントは IE で有効です。
js
let docType = document.implementation.createDocumentType("html", "", "");
let myDoc = document.implementation.createDocument("", "", docType);
docType.before(
document.createComment("<!--[if !IE]> conditional comment <![endif]-->"),
);
myDoc.childNodes;
// NodeList [<!--[if !IE]> conditional comment <![endif]-->, <!DOCTYPE html>]
仕様書
| Specification |
|---|
| DOM # ref-for-dom-childnode-before① |
ブラウザーの互換性
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