guardian/scribe

Typing backspace terminates the composition of IME for Chinese/Japanese

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#422 opened on Aug 15, 2015

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help wanted

Description

When I was typing Chinese and Japanese in scribe, I found that code in patches/events terminates the IME's composition in Chrome.

Typing CJK(Chinese/Japanese/Korean) characters need the help of IME, which buffers the user's keystrokes until a character or word has been made.The first line in the following example shows how IME works:

scribe

In the above example, I am trying to type sekai in Japanese. If I happen to type segai (in second line), I will press backspace to leave se there, then type kai to correct myself. Problem comes. The time I pressed backspace, the buffered keystrokes were lost(though they might still visually remain on the screen), leaving me no chance to continue from the last se I've already typed.

せ(se) か(ka) い(i)
せ(se) が(ga) い(i)

During the composition, keyup/keydown are fired in Chrome(reference: https://w3c.github.io/uievents/#events-composition-event-key-events). I guess placeMarkers and selectMarkers, which mutate the DOM, make the browser discard the buffers. By commenting these two lines in patches/events, composition is not influenced.

Removing these two lines may not be good solution. I'm thinking of a isComposing polyfill. If is composing, then we do not need to check whether the user is pressing backspace or not.

After:

scribe_correct

Now in the second line, after deleting gai, I could type kai right after se.

Contributor guide

Tech stack
javascript
Domain
frontendaccessibility
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
DOM eventsJavaScript
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
70
Research direction
The issue is located in `src/plugins/core/patches/events.js` around line 41. The `placeMarkers` and `selectMarkers` calls during DOM mutation break IME composition. A proposed solution is to add an `isComposing` check to skip these calls during composition. Investigate the `isComposing` property of the composition event or use a polyfill. Look at the browser's composition events API and how other editors handle this.