Japanese IME Undo during composition clears more text than expected
OS: macOS 14.0 · Device: Desktop or Laptop Any · Browser: Safari 17.0
Open case →Scenario
Undo and redo during IME composition
Pressing Undo or Redo while IME composition is active can cancel composition, leave partial syllables, or corrupt the undo stack. Behavior differs by browser and by whether the editor uses native undo or a custom history layer.
ime
Scenario ID
scenario-undo-with-composition
Details
Pressing Undo or Redo while IME composition is active can cancel composition, leave partial syllables, or corrupt the undo stack. Behavior differs by browser and by whether the editor uses native undo or a custom history layer.
Problem Overview
Composition is a transient state; undo systems expect discrete transactions. Mixing the two produces undefined interactions in the HTML editing spec space.
Observed Behavior
- Undo removes the composing text or the whole composition session unpredictably.
- Redo restores text that no longer matches IME state.
Impact
Lost input, confused users, and hard-to-reproduce bugs in Korean/Japanese/Chinese workflows.
Browser Comparison
Chromium, WebKit, and Gecko differ; mobile keyboards add variance.
Solutions
- While
isComposing, optionally block undo/redo shortcuts or queue them untilcompositionend. - Document-model editors should record undo steps only at composition boundaries when possible.
Related Cases
References
Scenario flow
Visual view of how this scenario connects to its concrete cases and environments. Nodes can be dragged and clicked.
Variants
Each row is a concrete case for this scenario, with a dedicated document and playground.
| Case | OS | Device | Browser | Keyboard | Status |
|---|---|---|---|---|---|
| ce-0007-undo-breaks-composition | Windows 11 | Desktop or Laptop Any | Chrome 120.0 | Korean (IME) | draft |
| ce-0208-korean-ime-undo-composition-chrome | Windows 11 | Desktop or Laptop Any | Chrome 120.0 | Korean (IME) | draft |
| ce-0209-japanese-ime-undo-composition-safari | macOS 14.0 | Desktop or Laptop Any | Safari 17.0 | Japanese (IME) | draft |
Browser compatibility
This matrix shows which browser and OS combinations have documented cases for this scenario. Click on a cell to view the specific case.
| Browser | Windows | macOS |
|---|---|---|
| Chrome | — | |
| Safari | — |
Confirmed
Draft
— No case documented
Cases
This scenario affects multiple languages. Cases are grouped by language/input method below.
Japanese
1 caseKorean
2 casesUndo during IME composition clears more text than expected
OS: Windows 11 · Device: Desktop or Laptop Any · Browser: Chrome 120.0
Open case →Korean IME Undo during composition clears more text than expected
OS: Windows 11 · Device: Desktop or Laptop Any · Browser: Chrome 120.0
Open case →Related Scenarios
Other scenarios that share similar tags or category.
Tags: ime, composition
beforeinput and input events have different inputType values
During IME composition or in certain browser/IME combinations, the beforeinput event may have a different inputType than the corresponding input event. For example, beforeinput may fire with insertCompositionText while input fires with deleteContentBackward. This mismatch can cause handlers to misinterpret the actual DOM change and requires storing beforeinput's targetRanges for use in input event handling.
1 case
Tags: ime, composition
Selection mismatch between beforeinput and input events
The selection (window.getSelection()) in beforeinput events can differ from the selection in corresponding input events. This mismatch can occur during IME composition, text prediction, or when typing adjacent to formatted elements like links. The selection in beforeinput may include adjacent formatted text, while input selection reflects the final cursor position.
1 case
Tags: ime, composition
beforeinput not cancelable during IME composition
Some beforeinput events during IME composition cannot be canceled per spec or implementation—calling preventDefault may throw or be ignored, so editors cannot always block native insertion.
1 case
Tags: ime, composition
Composition event lifecycle inconsistencies across browsers
Analysis of how out-of-order or missing composition events disrupt editor state synchronization.
2 cases
Tags: ime, composition
getTargetRanges() returns empty array in beforeinput events
The getTargetRanges() method in beforeinput events may return an empty array or undefined in various scenarios, including text prediction, certain IME compositions, or specific browser/device combinations. When getTargetRanges() is unavailable, developers must rely on window.getSelection() as a fallback, but this may be less accurate.
1 case
Comments & Discussion
Have questions, suggestions, or want to share your experience? Join the discussion below.