fix: backspace at start of nested list item deleted a char from the parent item

Fixes #1277

Author: xdan

CHANGELOG.md

@@ -9,6 +9,12 @@
 > - :house: [Internal]
 > - :nail_care: [Polish]
 
+## 4.12.14
+
+#### :bug: Bug Fix
+
+- **Backspace / Lists**: pressing Backspace at the start of a nested list item deleted the last character of the parent item instead of removing the nesting. `checkRemoveChar` walked out of the nested `<li>`/list and removed a character from the parent item's text. It no longer crosses a list-item boundary, so the list cases handle the operation cleanly. Fixes [#1277](https://github.com/xdan/jodit/issues/1277).
+
 ## 4.12.13
 
 #### :bug: Bug Fix

src/plugins/backspace/backspace.test.js

@@ -75,6 +75,10 @@ describe('Backspace/Delete key', function () {
 			'<ol><li>ab</li></ol><p>|cd</p> => <ol><li>ab|cd</li></ol>',
 			'<p>ab</p><ol><li>|cd</li></ol> => <p>ab</p><p>|cd</p>',
 			'<ol><li>ab</li><li>|cd</li></ol> => <ol><li>ab|cd</li></ol>',
+			// #1277: backspace at the start of a nested list item must not delete
+			// a character from the parent item across the list boundary.
+			'<ol><li>power<ol><li>|child</li></ol></li></ol> => <ol><li>power<p>|child</p></li></ol>',
+			'<ul><li>power<ul><li>|child</li></ul></li></ul> => <ul><li>power<p>|child</p></li></ul>',
 			'test<br>|plot => test|plot =>  => {"enter": "br"}',
 			'test<br>|plot => testtext|plot =>  => {"enter": "br"}  => text',
 			'test<br>p|lot => test<br>|lot =>  => {"enter": "br"}',

src/plugins/backspace/cases/check-remove-char.ts

@@ -133,6 +133,17 @@ function getNextInlineSibling(
 
 	if (!nextSibling && sibling.parentNode && sibling.parentNode !== root) {
 		nextSibling = findMostNestedNeighbor(sibling, !backspace, root, true);
+
+		// Do not cross a list-item boundary. At the start of a list item the
+		// neighbor can be the text of the parent/previous item; deleting a char
+		// there is wrong — the list cases must handle the outdent/merge (#1277).
+		if (
+			nextSibling &&
+			Dom.closest(sibling, 'li', root) !==
+				Dom.closest(nextSibling, 'li', root)
+		) {
+			return null;
+		}
 	}
 
 	return nextSibling;