Creating own Document Javascript

Question

So I am trying to use the Document() constructor method to create my own document but I fail at Illegal Invocation Error . Could someone explain this behavior?

mydom = new Document()
// TypeError: Illegal constructor
var MyDom = new Function()
// undefined
MyDom.prototype
// Object {}
MyDom.prototype = Document.prototype
// Document {createElement: function, createDocumentFragment: function, createTextNode:      function, createComment: function, createCDATASection: function…}
myowndom = new MyDom()
// Document {createElement: function, createDocumentFragment: function, createTextNode:    function, createComment: function, createCDATASection: function…}
myowndom.createElement('h1')
// TypeError: Illegal invocation
Document.prototype.constructor
// function Document() { [native code] }
myowndom.createAttribute.call(Document, "h1")
// TypeError: Illegal invocation

Answer 1

The Document function is not intended to be called , but is there only as a convenience variable. Documents are host objects (with a very complex underlying API) and are not easily constructed.

If you want to create an extra Document instance, you can use the document.implementation.createDocument() method for that.