fix: editor markdown not incrementing in a numbered list

Author: harryvince

web_src/js/features/comp/EditorMarkdown.test.ts

@@ -32,10 +32,10 @@ test('EditorMarkdown', () => {
   testInput({value: '1. \n2. ', pos: 3}, {value: '\n2. ', pos: 0});
 
   testInput('- x', '- x\n- ');
-  testInput('1. foo', '1. foo\n1. ');
-  testInput({value: '1. a\n2. b\n3. c', pos: 4}, {value: '1. a\n1. \n2. b\n3. c', pos: 8});
+  testInput('1. foo', '1. foo\n2. ');
+  testInput({value: '1. a\n2. b\n3. c', pos: 4}, {value: '1. a\n2. \n2. b\n3. c', pos: 8});
   testInput('- [ ]', '- [ ]\n- ');
   testInput('- [ ] foo', '- [ ] foo\n- [ ] ');
   testInput('* [x] foo', '* [x] foo\n* [ ] ');
-  testInput('1. [x] foo', '1. [x] foo\n1. [ ] ');
+  testInput('1. [x] foo', '1. [x] foo\n2. [ ] ');
 });

web_src/js/features/comp/EditorMarkdown.ts

@@ -96,8 +96,12 @@ function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
   } else {
     // start a new line with the same indention and prefix
     let newPrefix = prefix;
-    // a simple approach, otherwise it needs to parse the lines after the current line
-    if (/^\d+\./.test(prefix)) newPrefix = `1. ${newPrefix.slice(newPrefix.indexOf('.') + 2)}`;
+    const digitMatch = /^\d+/.exec(prefix);
+    if (digitMatch) {
+      const number = parseInt(digitMatch[0]);
+      const incremented = number + 1;
+      newPrefix = `${incremented}. ${newPrefix.slice(newPrefix.indexOf('.') + 2)}`;
+    }
     newPrefix = newPrefix.replace('[x]', '[ ]');
     const newLine = `\n${indention}${newPrefix}`;
     textarea.value = value.slice(0, selStart) + newLine + value.slice(selEnd);