Input Events Level 2

This document describes editing related additions to 2 events - input and beforeinput which are described in the UI events spec [UI-EVENTS]. The goal of these events is to allow authors to understand and/or override default edit behavior both before and after editing occurs.

As well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.

The key words MAY, MUST, and MUST NOT in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

express intention

A user can express an intention to execute a specific editing operation by means of keyboard, IME, speech, or similar method. Specific input actions are mapped to intentions following platform-specific conventions.

kill buffer

This definition is not normative.

A kill buffer is a in-memory store of richtext content that is separate from the clipboard which allows for the temporal storage of content that was deleted using specific deletion commands. The user can replace the current selection with the content held in the kill buffer by indicating an intention to yank the kill buffer.

This section is not normative.

Creating a webbased texteditor requires a considerable amount of JavaScript on top of the browser code, among other things because:

1. Browsers do not handle all editing operations the same way.
2. Browsers are often buggy in the way they handle certain editing operations.
3. Individual sites may have custom preferences for how they want to handle certain editing operations.
4. The development of high-level text editing features in browsers has not followed the principles laid out in the Extensible Web Manifesto in that development of these features has not always been in coordination with the needs of the web developer community.

This spec seeks to alleviate the problem by providing a simple way for web developers to both override browser handling of all user input related to text editing through the beforeinput event, and to monitor what browsers have changed in the DOM due to user input through the input event.

This section is not normative.

1. Creating a JavaScript text editor in which the <strong>-tag is used instead of the <b>-tag to mark text that the user marks as bold, using any browser-builtin way to mark a text as bold, without having access to all existing browsers.
2. Creating a JavaScript text editor which works with a data model in the background where JavaScript takes care of rendering changes to the edited text to the DOM.
3. Creating a JavaScript editor which only allows a subset of richtext editing (for example: bold is allowed, but italic not).
4. Creating a collaborative editor in which JavaScript is used to render changes to the DOM, based on user intentions with users using different browsers with different ways of expressing specific intentions.
5. Creating a JavaScript editor with different user access options, where some users only can add or delete text and other users only can add or remove certain types of formatting.

Input events are sent before (beforeinput event) and after (input event) a user attempts to edit the markup. This includes insertion and deletion of content, and formatting changes.

Input events are dispatched on elements that act as editing hosts, including elements with the contenteditable attribute set, textarea elements, and input elements that permit text input.

WebIDLpartial interface InputEvent {
   readonly attribute DataTransfer? dataTransfer;
   sequence<StaticRange> getTargetRanges();
};

partial dictionary InputEventInit {
   DataTransfer? dataTransfer = null;
   sequence<StaticRange> targetRanges = [];
};

The start of a composition is marked by dispatching a compositionstart event.

During a composition session, whenever a text composition system updates its active text passage, a compositionupdate event is dispatched.

After each compositionupdate event, a pair of beforeinput and input events are dispatched. The beforeinput and input events:

• Are not cancellable
• Have an inputType set to "insertCompositionText"
• Have a data attribute equal to that of the compositionupdate event
• Have a targetRange that surrounds the active text passage of the composition

The DOM contents of the active text passage are updated after the beforeinput event is dispatched and before the input event is dispatched.

The end of a composition session is marked by dispatching a compositionend event.

When an "insertFromPaste" beforeinput event is dispatched, it MUST be preceded by a paste [CLIPBOARD-APIS] event.

This section is not normative.

There are no known security or privacy impacts of this feature beyond fingerprinting [fingerprinting-guidance] techniques that already are available through existing events, such as the keydown and keypress [UI-EVENTS] events.

If this feature replaces existing events, it MAY lead to a decline in available fingerprinting [fingerprinting-guidance] techniques, as users' intentions are recorded, and not the particular type of hardware they used to express this intention.

Thanks to: Michael Aufreiter, Adrian Bateman, Oliver Buchtala, Robin Berjon, Enrica Casucci, Bo Cupp, Domenic Denicola, Emil Eklund, Olivier Forget, Aryeh Gregor, Marijn Haverbeke, Yoshifumi Inoue, Koji Ishii, Gary Kacmarcik, Ian Kilpatrick, Frederico Caldeira Knabben, Takayoshi Kochi, Piotrek Koszuliński, Travis Leithead, Grisha Lyukshin, Miles Maxfield, Chaals McCathie Nevile, Masayuki Nakano, Ryosuke Niwa, Julie Parent, Ben Peters, Florian Rivoal, Morgan Smith, Hallvord R. M. Steen, Johan Sörlin, Cristian Talau, Dave Tapuska, Ojan Vafai, Léonie Watson, Xiaoqian Wu, Chong Zhang, Joanmarie, and everyone in the Editing Taskforce for their input and feedback.