[lexical-markdown] Feature: Add $convertSelectionToMarkdownString API by mayrang · Pull Request #8395 · facebook/lexical

mayrang · 2026-04-27T04:46:08Z

Description

Adds a new $convertSelectionToMarkdownString function that converts only the selected content to a markdown string. Previously, $convertToMarkdownString could only convert the entire editor content.

What changed

Added $convertSelectionToMarkdownString(transformers, selection, shouldPreserveNewLines) to @lexical/markdown
Reuses existing markdown export logic (exportTopLevelElements, exportChildren, exportTextFormat) with selection filtering
Handles partial text selection by slicing text at anchor/focus offsets
Returns empty string for null or collapsed selections
Works inside editor.read() — no node creation needed

Usage

import {$convertSelectionToMarkdownString, TRANSFORMERS} from '@lexical/markdown';

editor.read(() => {
  const markdown = $convertSelectionToMarkdownString(TRANSFORMERS, $getSelection());
});

Implementation approach

Rather than creating a separate export pipeline, this extends the existing createMarkdownExport with an optional selection parameter. When provided, nodes are filtered via isSelected() and text content is sliced at selection boundaries. This provides a cleaner API for the use case described by @etrepum in #6503, without requiring editor.update() or manual node reconstruction.

Open to alternative approaches if a different direction is preferred.

Test Plan

Full text selection → returns full markdown
Partial text selection → returns sliced text
Bold text selection → preserves formatting
Null selection → returns empty string
Collapsed selection → returns empty string
Backward selection → correct slicing
Multi-paragraph selection → includes both paragraphs
List selection → preserves list markdown syntax

vercel · 2026-04-27T04:46:13Z

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Project	Deployment	Actions	Updated (UTC)
lexical	Ready	Preview, Comment	Apr 29, 2026 5:42am
lexical-playground	Ready	Preview, Comment	Apr 29, 2026 5:42am

mayrang · 2026-04-27T04:57:43Z

Not fully sure this is the right approach — feedback on the direction would be appreciated before going further.

etrepum · 2026-04-27T05:08:31Z

I won't have time to read through the code tonight but if it is following the same approach that HTML and JSON export takes then it's probably the right direction. If it's some other way then maybe not.

mayrang · 2026-04-27T06:07:56Z

Thanks — checked how HTML and JSON export handle this, they both use $sliceSelectedTextNodeContent with 'clone' mode. My initial version did the slicing manually, which worked but missed token/segmented node handling. Switching to $sliceSelectedTextNodeContent to stay consistent and cover those cases.

etrepum

I think there is probably some additional work that should be done to support extractWithChild to support situations like a partial LinkNode selection. I think taking the 'html' path makes the most sense for markdown (not 'clone').

Note that main has changed its prettier config so it might be easiest to copy over the new config, run prettier, commit, and then merge to sync.

mayrang · 2026-04-27T16:35:09Z

For extractWithChild — adding the check inside exportChildren gets messy with nested structures (e.g. link inside a list item), so I looked into restructuring the export like $appendNodesToHTML does. Problem is that changes the return type of exportChildren from string to object, which would break $convertToMarkdownString and any external transformers using the current callbacks.

Thinking the safest route is building the recursive structure separately for $convertSelectionToMarkdownString, keeping the existing export untouched. Some duplication (~50-70 lines) but no regression risk. Does that work, or do you have a different approach in mind?

etrepum · 2026-04-27T16:40:20Z

I think building something separate is probably best, and then we can worry about refactoring or deprecating the current implementation later. Eventually I think the markdown module will be changing a lot for correctness and flexibility reasons, so I don’t think we should care all that much about the existing code other than to keep it backwards compatible.

mayrang · 2026-04-27T18:29:37Z

Added extractWithChild support as a separate recursive path (createSelectionMarkdownExport), keeping the existing export untouched. Using $sliceSelectedTextNodeContent with 'clone' and extractWithChild with 'html' as suggested.

Went through the transformer implementations looking for edge cases — found one with the list transformer. It iterates children itself and adds - prefixes, so unselected items show up as empty prefixed lines (e.g. - \n- Item 2 instead of - Item 2). The CODE transformer also skips exportChildren and calls getTextContent() directly, so selection doesn't apply there.

To fix the list issue, the transformer callback would need to support skipping nodes, which means changing the (node) => string interface — breaking change for external transformers. Since the markdown module is getting a bigger refactor anyway, maybe this is better addressed then? Let me know what you think.

Added a test showing the current list behavior so you can see the edge case directly.

etrepum · 2026-04-27T19:03:27Z

Yeah, to that point, maybe it would be better to not add this API until we have better markdown infrastructure to support it.

I think in an ideal world we would have separate markdown shortcuts (that operate as you type) and markdown import/export (full document or selection import/export) infrastructure. They are very similar in theory but in practice trying to write code that does the right thing in both scenarios doesn't work very well. It would also be much easier to wire up a fully featured markdown implementation like remark or micromark to the import/export operations.

mayrang · 2026-04-27T19:11:48Z

Makes sense. Would it be useful to keep this as a draft until then, or better to close it entirely? The basic cases (text, formatting, links) work well — just wanted to check if there's value in having it available even with the list limitation.

etrepum · 2026-04-27T19:28:52Z

Up to you whether you keep it draft or close it. I don't think it can work correctly without refactoring other parts as you've noted. Maybe there's a possible refactoring of the existing transformer interface that allows this to work (adding an argument wouldn't necessarily break existing transformers or their types), if you want to look into that it would be a good interim solution for anyone looking for this functionality.

mayrang · 2026-04-27T20:31:51Z

Thanks for the pointer on the transformer interface — added an optional selection parameter to ElementTransformer.export and updated $listExport to skip unselected items when provided. Since the parameter is optional, existing transformers work as-is. Nested lists are handled correctly too.

The list edge case from earlier is now fixed.

etrepum

Overall this looks great, a welcome addition to the current API. All of the comments are really just syntax nits and simplifications

etrepum · 2026-04-28T02:10:45Z

 ): void;

+declare export function $convertSelectionToMarkdownString(
+  transformers?: Array<Transformer>,


Current flow syntax and conventions are much closer to Typescript

Suggested change

transformers?: Array<Transformer>,

transformers?: Transformer[],

etrepum · 2026-04-28T02:13:49Z

+        normal.select(0, 6);
+        const selection = $getSelection();
+        if ($isRangeSelection(selection)) {
+          selection.focus.set(bold.getKey(), 4, 'text');
+        }


Suggested change

normal.select(0, 6);

const selection = $getSelection();

if ($isRangeSelection(selection)) {

selection.focus.set(bold.getKey(), 4, 'text');

}

const selection = normal.select(0, 6);

selection.focus.set(bold.getKey(), 4, 'text');

or alternatively you could use the NodeCaret APIs:

$setSelectionFromCaretRange( $getCaretRange( $getTextPointCaret(normal, 'next', 0), $getTextPointCaret(bold, 'next', 4), ) );

Switched to NodeCaret API.

Went with this approach, cleaner to read.

etrepum · 2026-04-28T02:17:47Z

+        p2.append(t2);
+        root.append(p1, p2);
+        // Select from "First" to "Second"
+        t1.select(0, 15);


see above for simpler ways to create this RangeSelection

etrepum · 2026-04-28T02:17:56Z

+        item2.append(t2);
+        list.append(item1, item2);
+        root.append(list);
+        t1.select(0, 6);


see above for simpler ways to create this RangeSelection

etrepum · 2026-04-28T02:18:33Z

+        list.append(item1, item2, item3);
+        root.append(list);
+        // Select only "Item 2" and partial "Item 3"
+        t2.select(0, 6);


see above for simpler ways to create this RangeSelection

etrepum · 2026-04-28T02:22:03Z

+  if (!selection) {
+    return '';
+  }
+  if ($isRangeSelection(selection) && selection.isCollapsed()) {
+    return '';
+  }


These can be fused to save a few bytes

Suggested change

if (!selection) {

return '';

}

if ($isRangeSelection(selection) && selection.isCollapsed()) {

return '';

}

if (!selection || $isRangeSelection(selection) && selection.isCollapsed()) {

return '';

}

etrepum · 2026-04-28T02:22:22Z

+ * inline elements like links.
+ */
+export function createSelectionMarkdownExport(
+  transformers: Array<Transformer>,


Suggested change

transformers: Array<Transformer>,

transformers: Transformer[],

etrepum · 2026-04-28T02:23:40Z

+  elementTransformers: Array<ElementTransformer | MultilineElementTransformer>,
+  textFormatTransformers: Array<TextFormatTransformer>,
+  textMatchTransformers: Array<TextMatchTransformer>,


Suggested change

elementTransformers: Array<ElementTransformer | MultilineElementTransformer>,

textFormatTransformers: Array<TextFormatTransformer>,

textMatchTransformers: Array<TextMatchTransformer>,

elementTransformers: (ElementTransformer | MultilineElementTransformer)[],

textFormatTransformers: TextFormatTransformer[],

textMatchTransformers: TextMatchTransformer[],

etrepum · 2026-04-28T02:24:33Z

+      _node =>
+        $exportChildrenForSelection(
+          _node,


underscore prefix is for unused variables, shouldn't really be used when just avoiding shadowing

Suggested change

_node =>

$exportChildrenForSelection(

_node,

node_ =>

$exportChildrenForSelection(

node_,

Makes sense, fixed.

etrepum · 2026-04-28T02:25:22Z

+  textFormatTransformers: Array<TextFormatTransformer>,
+  textMatchTransformers: Array<TextMatchTransformer>,
+  shouldPreserveNewLines: boolean,
+  unclosedTags?: Array<{format: TextFormatType; tag: string}>,
+  unclosableTags?: Array<{format: TextFormatType; tag: string}>,


Suggested change

textFormatTransformers: Array<TextFormatTransformer>,

textMatchTransformers: Array<TextMatchTransformer>,

shouldPreserveNewLines: boolean,

unclosedTags?: Array<{format: TextFormatType; tag: string}>,

unclosableTags?: Array<{format: TextFormatType; tag: string}>,

textFormatTransformers: TextFormatTransformer[],

textMatchTransformers: TextMatchTransformer[],

shouldPreserveNewLines: boolean,

unclosedTags?: {format: TextFormatType; tag: string}[],

unclosableTags?: {format: TextFormatType; tag: string}[],

mayrang · 2026-04-28T03:44:47Z

All addressed, force-pushed. Thanks for the review!

Add a new function that converts only the selected content to a markdown string, reusing existing export logic with selection filtering. Handles partial text selection by slicing at anchor/focus offsets and returns empty string for null or collapsed selections. Fixes facebook#6503

mayrang requested review from acywatson, etrepum, fantactuka, ivailop7, potatowagon, takuyakanbr and zurfyx as code owners April 27, 2026 04:46

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Merge branch 'main' into feat/selection-to-markdown

3543533

etrepum added the extended-tests Run extended e2e tests on a PR label Apr 28, 2026

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Merged via the queue into facebook:main with commit 838b19e Apr 29, 2026
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etrepum mentioned this pull request Apr 29, 2026

[lexical-markdown] Bug Fix: Preserve hard line breaks in default markdown import #8402

Merged

	transformers?: Array<Transformer>,
	transformers?: Transformer[],

	transformers: Array<Transformer>,
	transformers: Transformer[],

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Description

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Usage

Implementation approach

Test Plan

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