w3c reference : https://www.w3.org/TR/2014/REC-html5-20141028/introduction.html#writing-secure-applications-with-html
HTML user agents (e.g. Web browsers) then parse this markup, turning it into a DOM (Document Object Model) tree. A DOM tree is an in-memory representation of a document.
DOM trees contain several kinds of nodes, in particular a DocumentType
node, Element
nodes, Text
nodes, Comment
nodes, and in some cases ProcessingInstruction
nodes.
- DOCTYPE:
html
html
The root element of this tree is the html
element, which is the element always found at the root of HTML documents. It contains two elements, head
and body
, as well as a Text
node between them.
The root element of this tree is the html
element, which is the element always found at the root of HTML documents. It contains two elements, head
and body
, as well as a Text
node between them.
There are many more Text
nodes in the DOM tree than one would initially expect, because the source contains a number of spaces (represented here by "?") and line breaks ("?") that all end up as Text
nodes in the DOM. However, for historical reasons not all of the spaces and line breaks in the original markup appear in the DOM. In particular, all the whitespace before head
start tag ends up being dropped silently, and all the whitespace after the body
end tag ends up placed at the end of the body
.