A feature history of the modern Web Platform

When and where selected new Web-platform features were first specified, post-HTML4 and post-CSS2.1.

2003-09-05 XHTML Module: Extensions to Form Controls

The post-HTML4/CSS2.1 Web Platform spec history begins with these additions to the HTML language:

datetime, date, expdate, time, number, integer, and email values for the type attribute of the input element
minimum and maximum attributes of the input element (soon after renamed to just min and max)
editable attribute for the select element (later dropped)
wrap attribute for the textarea element
pattern attribute for text-input controls
required attribute for form controls
form attribute for form controls
autocomplete attribute for form controls
inputmode attribute for text-input controls (later dropped)
help attribute for form controls (borrowed from XForms, later dropped)
client-side HTML form validation

2003-12-03 Proposed XHTML Module: XForms Basic

uri value for the type attribute of the input element (later renamed to url)
output element
XForms 1.0 (2001-06-08 sixth WD) was first to have an output element

2004-02-05 Web Forms 2.0

week value for the type attribute of the input element
tel value for the type attribute of the input element (later dropped but then later re-added)
location value for the type attribute of the input element (later dropped)
precision attribute for the input element (later renamed to step)
replace attribute for the form element (later dropped)

2004-03-09 Web Forms 2.0

2004-04-07 Web Applications Markup Language 1.0

2004-06-27 Web Forms 2.0

local-datetime value for the type attribute of the input element (later renamed to datetime-local)
month value for the type attribute of the input element
autofocus attribute for form controls

2004-09-23 Web Applications 1.0

<!DOCTYPE html PUBLIC "-//WHATWG//NONSGML HTML5//EN"> (later changed)
command attribute (later dropped but then later re-added)
command element
commandset element (later dropped)
button element
menu element
menulabel element (later dropped)
menubar element (later dropped)
section element
XHTML 2.0 (2004-07-22 sixth public working draft) had a section element
tabbox element (later dropped)
switch element (later dropped)
canvas element
event-source element (later dropped)
server-sent events
getElementsByClass method (later renamed to getElementsByClassName)
Window interface (first specified)
XMLHttpRequest interface (first specified)

navigation element (later renamed to nav)
header element
footer element
article element
sidebar element (later renamed to aside)
calendar element (later dropped)
card element (later dropped)
inline data idea (placeholder for “where elements such as <date> or <time> might be defined”)
gauge element (later renamed to meter)
progress meters (placeholder)
data grids/trees (placeholder)
context-menu attribute (later renamed to contextmenu)
contentEditable attribute (first specified; later renamed to contenteditable)
ElementTraversal interface
Audio interface (later changed to HTMLAudioElement)
Connection interface (later changed to WebSocket)

2004-12-10 Web Forms 2.0