make code easier to test

Author: wxiaoguang

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

@@ -1,4 +1,4 @@
-import {initTextareaMarkdown} from './EditorMarkdown.ts';
+import {initTextareaMarkdown, markdownHandleListNumbers} from './EditorMarkdown.ts';
 
 test('EditorMarkdown', () => {
   const textarea = document.createElement('textarea');
@@ -33,9 +33,12 @@ test('EditorMarkdown', () => {
 
   testInput('- x', '- x\n- ');
   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({value: '1. a\n2. b\n3. c', pos: 4}, {value: '1. a\n2. \n3. b\n4. c', pos: 8});
   testInput('- [ ]', '- [ ]\n- ');
   testInput('- [ ] foo', '- [ ] foo\n- [ ] ');
   testInput('* [x] foo', '* [x] foo\n* [ ] ');
   testInput('1. [x] foo', '1. [x] foo\n2. [ ] ');
+
+  // TODO: test separately
+  markdownHandleListNumbers({value: '1.', selStart: 1, selEnd: 2});
 });

web_src/js/features/comp/EditorMarkdown.ts

@@ -14,7 +14,13 @@ export function textareaInsertText(textarea, value) {
   triggerEditorContentChanged(textarea);
 }
 
-function handleIndentSelection(textarea, e) {
+type TextareaValueSelection = {
+  value: string;
+  selStart: number;
+  selEnd: number;
+}
+
+function handleIndentSelection(textarea: HTMLTextAreaElement, e) {
   const selStart = textarea.selectionStart;
   const selEnd = textarea.selectionEnd;
   if (selEnd === selStart) return; // do not process when no selection
@@ -56,18 +62,21 @@ function handleIndentSelection(textarea, e) {
   triggerEditorContentChanged(textarea);
 }
 
-function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
-  const selStart = textarea.selectionStart;
-  const selEnd = textarea.selectionEnd;
-  if (selEnd !== selStart) return; // do not process when there is a selection
+type MarkdownHandleListNumbersResult = {
+  handled: boolean;
+  valueSelection?: TextareaValueSelection;
+}
 
-  const value = textarea.value;
+export function markdownHandleListNumbers(tvs: TextareaValueSelection): MarkdownHandleListNumbersResult {
+  const ret: MarkdownHandleListNumbersResult = {handled: false};
+  if (tvs.selEnd !== tvs.selStart) return ret; // do not process when there is a selection
 
+  const value = tvs.value;
   // find the current line
   // * if selStart is 0, lastIndexOf(..., -1) is the same as lastIndexOf(..., 0)
   // * if lastIndexOf reruns -1, lineStart is 0 and it is still correct.
-  const lineStart = value.lastIndexOf('\n', selStart - 1) + 1;
-  let lineEnd = value.indexOf('\n', selStart);
+  const lineStart = value.lastIndexOf('\n', tvs.selStart - 1) + 1;
+  let lineEnd = value.indexOf('\n', tvs.selStart);
   lineEnd = lineEnd < 0 ? value.length : lineEnd;
   let line = value.slice(lineStart, lineEnd);
   if (!line) return; // if the line is empty, do nothing, let the browser handle it
@@ -82,17 +91,20 @@ function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
   let prefix = '';
   if (prefixMatch) {
     prefix = prefixMatch[0];
-    if (lineStart + prefix.length > selStart) prefix = ''; // do not add new line if cursor is at prefix
+    if (lineStart + prefix.length > tvs.selStart) prefix = ''; // do not add new line if cursor is at prefix
   }
 
   line = line.slice(prefix.length);
-  if (!indention && !prefix) return; // if no indention and no prefix, do nothing, let the browser handle it
+  if (!indention && !prefix) return ret; // if no indention and no prefix, do nothing, let the browser handle it
 
-  e.preventDefault();
+  ret.handled = true;
   if (!line) {
     // clear current line if we only have i.e. '1. ' and the user presses enter again to finish creating a list
-    textarea.value = value.slice(0, lineStart) + value.slice(lineEnd);
-    textarea.setSelectionRange(selStart - prefix.length, selStart - prefix.length);
+    ret.valueSelection = {
+      value: value.slice(0, lineStart) + value.slice(lineEnd),
+      selStart: tvs.selStart - prefix.length,
+      selEnd: tvs.selStart - prefix.length,
+    };
   } else {
     // start a new line with the same indention and prefix
     let newPrefix = prefix;
@@ -104,9 +116,21 @@ function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
     }
     newPrefix = newPrefix.replace('[x]', '[ ]');
     const newLine = `\n${indention}${newPrefix}`;
-    textarea.value = value.slice(0, selStart) + newLine + value.slice(selEnd);
-    textarea.setSelectionRange(selStart + newLine.length, selStart + newLine.length);
+    ret.valueSelection = {
+      value: value.slice(0, tvs.selStart) + newLine + value.slice(tvs.selEnd),
+      selStart: tvs.selStart + newLine.length,
+      selEnd: tvs.selStart + newLine.length,
+    };
   }
+  return ret;
+}
+
+function handleNewline(textarea: HTMLTextAreaElement, e: Event) {
+  const ret = markdownHandleListNumbers({value: textarea.value, selStart: textarea.selectionStart, selEnd: textarea.selectionEnd});
+  if (!ret.handled) return;
+  e.preventDefault();
+  textarea.value = ret.valueSelection.value;
+  textarea.setSelectionRange(ret.valueSelection.selStart, ret.valueSelection.selEnd);
   triggerEditorContentChanged(textarea);
 }