Highlight DOM Nodes onHover of Lexical DevTools Node

packages/lexical-devtools/src/devtools/index.ts

@@ -16,46 +16,118 @@ chrome.devtools.panels.create(
   },
 );
 
+chrome.runtime.onConnect.addListener((port) => {
+  port.onMessage.addListener((message) => {
+    if (message.name === 'highlight') {
+      chrome.devtools.inspectedWindow.eval(`
+        highlight('${message.lexicalKey}');
+      `);
+    }
+
+    if (message.name === 'dehighlight') {
+      chrome.devtools.inspectedWindow.eval(`
+        dehighlight();
+      `);
+    }
+  });
+});
+
 function handleShown() {
-  // Use devtools.inspectedWindow.eval() to get editorState updates. For more info on security concerns:
+  // Security concerns related to chrome.devtools.inspectedWindow.eval():
   //   https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/Content_scripts
   //   https://developer.mozilla.org/en-US/docs/Mozilla/Add-ons/WebExtensions/API/devtools/inspectedWindow/eval
-  chrome.devtools.inspectedWindow
-    // Attach a registerUpdateListener within the window to subscribe to changes in editorState.
-    // After the initial registration, all editorState updates are done via browser.runtime.onConnect & window.postMessage
-    .eval(
-      `
-      const editor = document.querySelectorAll('div[data-lexical-editor]')[0]
-        .__lexicalEditor;
-
-      const initialEditorState = editor.getEditorState();
-
-      // custom JSON serialization
-      // existing editorState.toJSON() does not contain Lexical ._key property
-      const serializeEditorState = (editorState) => {
-        const nodeMap = Object.fromEntries(editorState._nodeMap);
-        return {nodeMap};
-      };
-
+
+  // query document for Lexical editor instance.
+  // TODO: add support multiple Lexical editors within the same page
+  // lexicalKey is attached to each DOM node like so: DOMNode[__lexicalKey_{editorKey}]
+  chrome.devtools.inspectedWindow.eval(`
+    const editorDOMNode = document.querySelectorAll(
+      'div[data-lexical-editor]',
+    )[0];
+    const editor = editorDOMNode.__lexicalEditor;
+    const editorKey = editorDOMNode.__lexicalEditor._key;
+    const lexicalKey = '__lexicalKey_' + editorKey;
+  `);
+
+  // depth first search to find DOM node with lexicalKey
+  chrome.devtools.inspectedWindow.eval(`
+    const findDOMNode = (node, targetKey) => {
+      if (targetKey === 'root') {
+        return editorDOMNode;
+      }
+
+      if (node[lexicalKey] && node[lexicalKey] === targetKey) {
+        return node;
+      }
+
+      for (let i = 0; i < node.childNodes.length; i++) {
+        const child = findDOMNode(node.childNodes[i], targetKey);
+        if (child) return child;
+      }
+
+      return null;
+    };
+  `);
+
+  // functions to highlight/dehighlight DOM nodes onHover of DevTools nodes
+  chrome.devtools.inspectedWindow.eval(`
+    const highlight = (lexicalKey) => {
+      const node = findDOMNode(editorDOMNode, lexicalKey);
+      const {width, height, top, left} = node.getBoundingClientRect();
+      highlightOverlay.style.width = width + 'px';
+      highlightOverlay.style.height = height + 'px';
+      highlightOverlay.style.top = top + window.scrollY + 'px';
+      highlightOverlay.style.left = left + window.scrollX + 'px';
+      highlightOverlay.style.display = 'block';
+    };
+
+    const dehighlight = () => {
+      highlightOverlay.style.display = 'none';
+    };
+  `);
+
+  // append highlight overlay <div> to document
+  chrome.devtools.inspectedWindow.eval(`
+    const highlightOverlay = document.createElement('div');
+    highlightOverlay.style.position = 'absolute';
+    highlightOverlay.style.background = 'rgba(119, 182, 255, 0.5)';
+    highlightOverlay.style.border = '1px dashed #77b6ff';
+    document.body.appendChild(highlightOverlay);
+  `);
+
+  // send initial editorState to devtools app through window.postMessage.
+  // the existing editorState.toJSON() does not contain lexicalKey
+  // therefore, we have a custom serializeEditorState helper
+  chrome.devtools.inspectedWindow.eval(`
+    const initialEditorState = editor.getEditorState();
+
+    const serializeEditorState = (editorState) => {
+      const nodeMap = Object.fromEntries(editorState._nodeMap);
+      return {nodeMap};
+    };
+
+    window.postMessage(
+      {
+        editorState: serializeEditorState(initialEditorState),
+        name: 'editor-update',
+        type: 'FROM_PAGE',
+      },
+      '*',
+    );
+  `);
+
+  // Attach a registerUpdateListener within the window to subscribe to changes in editorState.
+  // After the initial registration, all editorState updates are done via browser.runtime.onConnect & window.postMessage
+  chrome.devtools.inspectedWindow.eval(`
+    editor.registerUpdateListener(({editorState}) => {
       window.postMessage(
         {
-          editorState: serializeEditorState(initialEditorState),
+          editorState: serializeEditorState(editorState),
           name: 'editor-update',
           type: 'FROM_PAGE',
         },
         '*',
       );
-
-      editor.registerUpdateListener(({editorState}) => {
-        window.postMessage(
-          {
-            editorState: serializeEditorState(editorState),
-            name: 'editor-update',
-            type: 'FROM_PAGE',
-          },
-          '*',
-        );
-      });
-    `,
-    ); // to do: add error handling eg. .then(handleError)
+    });
+  `);
 }

packages/lexical-devtools/src/panel/components/App/index.tsx

@@ -9,7 +9,7 @@ import './index.css';
 
 import {DevToolsTree} from 'packages/lexical-devtools/types';
 import * as React from 'react';
-import {useEffect, useRef, useState} from 'react';
+import {useCallback, useEffect, useRef, useState} from 'react';
 
 import TreeView from '../TreeView';
 
@@ -26,6 +26,30 @@ function App(): JSX.Element {
     setNodeMap(newNodeMap);
   };
 
+  // highlight & dehighlight the corresponding DOM nodes onHover of DevTools nodes
+  const highlightDOMNode = useCallback(
+    (lexicalKey: string) => {
+      port.current?.postMessage({
+        lexicalKey,
+        name: 'highlight',
+        tabId: window.chrome.devtools.inspectedWindow.tabId,
+        type: 'FROM_APP',
+      });
+    },
+    [port],
+  );
+
+  const deHighlightDOMNode = useCallback(
+    (lexicalKey: string) => {
+      port.current?.postMessage({
+        name: 'dehighlight',
+        tabId: window.chrome.devtools.inspectedWindow.tabId,
+        type: 'FROM_APP',
+      });
+    },
+    [port],
+  );
+
   useEffect(() => {
     // create and initialize the messaging port to receive editorState updates
     port.current = window.chrome.runtime.connect();
@@ -64,7 +88,12 @@ function App(): JSX.Element {
           <p>Loading...</p>
         </div>
       ) : (
-        <TreeView viewClassName="tree-view-output" nodeMap={nodeMap} />
+        <TreeView
+          deHighlightDOMNode={deHighlightDOMNode}
+          highlightDOMNode={highlightDOMNode}
+          viewClassName="tree-view-output"
+          nodeMap={nodeMap}
+        />
       )}
     </div>
   );

packages/lexical-devtools/src/panel/components/Chevron/index.css

@@ -7,3 +7,8 @@
   padding: 0;
   text-decoration: none;
 }
+
+.tree-node:hover > .chevron-button {
+  background: #77b6ff;
+  color: #222;
+}

packages/lexical-devtools/src/panel/components/TreeNode/index.css

@@ -8,11 +8,17 @@
   user-select: none;
 }
 
-.tree-node {
-  padding-left: 1em;
-  width: 100%;
+.tree-node:hover {
+  background: #77b6ff;
+  color: #222;
 }
 
 .tree-node-wrapper {
+  cursor: pointer;
+  white-space: nowrap;
   width: 100%;
 }
+
+.tree-node-wrapper:first-child {
+  width: 100vw;
+}

packages/lexical-devtools/src/panel/components/TreeNode/index.tsx

@@ -17,15 +17,26 @@ function TreeNode({
   __text,
   __type,
   children,
+  deHighlightDOMNode,
   depth,
+  highlightDOMNode,
   lexicalKey,
+  monospaceWidth,
 }: DevToolsNode): JSX.Element {
   const [isExpanded, setIsExpanded] = useState(true);
 
   const handleChevronClick = () => {
     setIsExpanded(!isExpanded);
   };
 
+  const handleMouseEnter: React.MouseEventHandler = (event) => {
+    highlightDOMNode(lexicalKey);
+  };
+
+  const handleMouseLeave: React.MouseEventHandler = (event) => {
+    deHighlightDOMNode(lexicalKey);
+  };
+
   const nodeString = ` (${lexicalKey}) ${__type} ${
     __text ? '"' + __text + '"' : ''
   }`;
@@ -40,15 +51,25 @@ function TreeNode({
       ''
     );
 
+  const leftIndent = depth * parseFloat(monospaceWidth) + 'em';
+
   return (
-    <div className="tree-node" key={lexicalKey}>
-      {children.length > 0 ? (
-        <Chevron handleClick={handleChevronClick} isExpanded={isExpanded} />
-      ) : (
-        <button className="indentation">&#9654;</button>
-      )}
-      {nodeString}
-      {<br />}
+    <div className="tree-node-wrapper" key={lexicalKey}>
+      <div
+        className="tree-node"
+        onMouseEnter={handleMouseEnter}
+        onMouseLeave={handleMouseLeave}
+        style={{paddingLeft: leftIndent}}>
+        <span style={{width: 'var(--monospace-character-width)'}}>&nbsp;</span>
+        {children.length > 0 ? (
+          <Chevron handleClick={handleChevronClick} isExpanded={isExpanded} />
+        ) : (
+          <span style={{width: 'var(--monospace-character-width)'}}>
+            &nbsp;
+          </span>
+        )}
+        {nodeString}
+      </div>
       {isExpanded ? childNodes : ''}
     </div>
   );

packages/lexical-devtools/src/panel/components/TreeView/index.css

@@ -3,11 +3,11 @@
   background: #222;
   color: #fff;
   margin: 0;
-  padding: 1em;
+  padding: 1em 0;
   font-size: 1.2em;
   overflow: auto;
   text-align: left;
   -moz-osx-font-smoothing: grayscale;
   font-weight: 400;
-  --indentation-size: 1em;
+  width: max-content;
 }

packages/lexical-devtools/src/panel/components/TreeView/index.tsx

@@ -13,12 +13,21 @@ import * as React from 'react';
 import TreeNode from '../TreeNode';
 
 function TreeView({
+  deHighlightDOMNode,
+  highlightDOMNode,
   viewClassName,
   nodeMap,
 }: {
+  deHighlightDOMNode: (lexicalKey: string) => void;
+  highlightDOMNode: (lexicalKey: string) => void;
   viewClassName: string;
   nodeMap: DevToolsTree;
 }): JSX.Element {
+  // read CSS variable from the DOM in order to pass it to TreeNode
+  const monospaceWidth = getComputedStyle(
+    document.documentElement,
+  ).getPropertyValue('--monospace-character-width');
+
   // takes flat JSON structure, nests child comments inside parents
   const depthFirstSearch = (
     map: DevToolsTree = nodeMap,
@@ -38,8 +47,11 @@ function TreeView({
       ...node,
       __type: node.__type,
       children,
+      deHighlightDOMNode,
       depth,
+      highlightDOMNode,
       lexicalKey: node.__key,
+      monospaceWidth,
     };
   };
 

packages/lexical-devtools/src/panel/components/main/index.css

@@ -1,3 +1,7 @@
+:root {
+  --monospace-character-width: 1.2em;
+}
+
 body {
   margin: 0;
   font-family: monospace;

packages/lexical-devtools/types.ts

@@ -15,6 +15,9 @@ export interface DevToolsNode {
   __text?: string;
   __type: string;
   children: Array<DevToolsNode>;
+  deHighlightDOMNode: (lexicalKey: string) => void;
   depth: number;
+  highlightDOMNode: (lexicalKey: string) => void;
   lexicalKey: string;
+  monospaceWidth: string;
 }