The DocumentType.before() method inserts a set of Node or DOMString objects in the children list of the DocumentType's parent, just before the DocumentType. DOMString objects are inserted as equivalent Text nodes.
Note: Putting nodes before the document's doctype will set the rendering mode to quirks mode in some browsers (Internet Explorer). It is not advisable to do this.
before(... nodes)
HierarchyRequestError
DOMException
Thrown when the node cannot be inserted at the specified point in the hierarchy.
Comment nodes are valid before doctype declarations but not advisable given they trigger quirks mode in IE. A conditional comment works for IE as well, though:
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>]
| Specification |
|---|
| DOM Standard # ref-for-dom-childnode-before① |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
before |
54
|
17
|
49
|
No
|
39
|
10
|
54
|
54
|
49
|
41
|
10
|
6.0
|
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https://developer.mozilla.org/en-US/docs/Web/API/DocumentType/before
| Name | Web APIs |
| Version | |
| Badge |
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| Last Updated | 2022-04-27T09:33:08Z |