Document.doctype

Returns the Document Type Declaration (DTD) associated with current document. The returned object implements the DocumentType interface. Use DOMImplementation.createDocumentType() to create a DocumentType.

doctype = document.doctype;

• doctype is a read-only property.

var doctypeObj = document.doctype;

console.log(
  "doctypeObj.name: "           + doctypeObj.name            + "\n" +
  "doctypeObj.internalSubset: " + doctypeObj.internalSubset  + "\n" +
  "doctypeObj.publicId: "       + doctypeObj.publicId        + "\n" +
  "doctypeObj.systemId: "       + doctypeObj.systemId
);

The property returns null if there is no DTD associated with the current document.

DOM level 2 doesn't support editing the document type declaration.