Add configurable highlight support

app/assets/stylesheets/lexxy-editor.css

@@ -463,6 +463,10 @@
     display: none;
   }
 
+  &[data-highlight="false"] .lexxy-editor__toolbar-dropdown--highlight {
+    display: none;
+  }
+
   &[data-upload="file"] button[name="image"] {
     display: none;
   }

docs/configuration.md

@@ -50,6 +50,7 @@ Editors support the following options, configurable using presets and element at
 - `multiLine`: Pass `false` to force single line editing.
 - `permittedAttachmentTypes`: Restrict the editor to a specific allowlist of attachment content types. Unset (the default) permits any content type. Example: `<lexxy-editor permitted-attachment-types="application/vnd.basecamp.mention application/vnd.basecamp.opengraph-embed"></lexxy-editor>`.
 - `richText`: Pass `false` to disable rich text editing.
+- `highlight`: Color highlighting configuration. Pass `{ enabled: false }` (or simply `false`) to disable highlighting entirely (it is enabled by default). See [Highlighting](highlighting.md) for configuring the available colors.
 
 The toolbar is considered part of the editor for `lexxy:focus` and `lexxy:blur` events. If the toolbar registers event or lexical handlers, it should expose a `dispose()` function which will be called on editor disconnect.
 

docs/highlighting.md

@@ -32,3 +32,19 @@ Lexxy.configure({
   }
 })
 ```
+
+## Disabling highlighting
+
+Pass `highlight.enabled: false` to disable color highlighting entirely. The toolbar control is hidden, the commands become inert, and existing highlight markup is reduced to plain text on load.
+
+```javascript
+Lexxy.configure({
+  default: {
+    highlight: { enabled: false }
+  }
+})
+```
+
+Or per editor: `<lexxy-editor highlight='{"enabled":false}'></lexxy-editor>`.
+
+A bare boolean is also accepted as a shorthand — `highlight: false` in a preset, or `<lexxy-editor highlight="false">`.

src/config/lexxy.js

@@ -19,6 +19,7 @@ const presets = new Configuration({
       upload: "both"
     },
     highlight: {
+      enabled: true,
       buttons: {
         color: range(1, 9).map(n => `var(--highlight-${n})`),
         "background-color": range(1, 9).map(n => `var(--highlight-bg-${n})`),

src/elements/dropdown/highlight.js

@@ -14,6 +14,8 @@ const NO_STYLE = Symbol("no_style")
 
 export class HighlightDropdown extends ToolbarDropdown {
   editorReady() {
+    if (!this.editorElement.supportsHighlight) return
+
     this.#setUpButtons()
     this.#registerButtonHandlers()
   }
@@ -34,6 +36,7 @@ export class HighlightDropdown extends ToolbarDropdown {
     this.#buttonContainer.innerHTML = ""
 
     const colorGroups = this.editorElement.config.get("highlight.buttons")
+    if (!colorGroups) return
 
     this.#populateButtonGroup("color", colorGroups.color)
     this.#populateButtonGroup("background-color", colorGroups["background-color"])

src/elements/editor.js

@@ -3,6 +3,7 @@ import { buildEditorFromExtensions } from "@lexical/extension"
 import { ListItemNode, ListNode, registerList } from "@lexical/list"
 import { AutoLinkNode, LinkNode } from "@lexical/link"
 import { $getNearestNodeOfType } from "@lexical/utils"
+import { getCSSFromStyleObject, getStyleObjectFromCSS } from "@lexical/selection"
 import { registerPlainText } from "@lexical/plain-text"
 import { HeadingNode, QuoteNode, registerRichText } from "@lexical/rich-text"
 import { $generateHtmlFromNodes, $generateNodesFromDOM as $generateLexicalNodesFromDOM } from "@lexical/html"
@@ -260,6 +261,13 @@ export class LexicalEditorElement extends HTMLElement {
     return this.config.get("richText")
   }
 
+  get supportsHighlight() {
+    // Accept both the object form ({ enabled: false }) and a bare boolean (highlight: false),
+    // mirroring the scalar-disable convention used by the sibling options.
+    const highlight = this.config.get("highlight")
+    return this.supportsRichText && highlight !== false && highlight?.enabled !== false
+  }
+
   registerAdapter(adapter) {
     this.adapter = adapter
 
@@ -407,6 +415,7 @@ export class LexicalEditorElement extends HTMLElement {
         export: new Map([ [ TextNode, exportTextNodeDOM ], [ CodeHighlightNode, exportTextNodeDOM ] ])
       },
       $initialEditorState: (editor) => {
+        this.#removeDisabledConversions(editor)
         this.#configureSanitizer(editor)
         this.#loadInitialValue(editor)
         this.#setInternalFormValue(this.#readSanitizedEditorValue(editor))
@@ -576,6 +585,7 @@ export class LexicalEditorElement extends HTMLElement {
         registerRichText(this.editor),
         registerList(this.editor)
       )
+      this.#registerDisabledHighlightStripper(registered)
       this.#registerTableComponents()
       this.#registerCodeHiglightingComponents()
       if (this.supportsMarkdown) {
@@ -716,6 +726,7 @@ export class LexicalEditorElement extends HTMLElement {
     const toolbar = createElement("lexxy-toolbar")
     toolbar.innerHTML = LexicalToolbar.defaultTemplate
     toolbar.setAttribute("data-attachments", this.supportsAttachments) // Drives toolbar CSS styles
+    toolbar.setAttribute("data-highlight", this.supportsHighlight) // Drives toolbar CSS styles
     toolbar.configure(this.config.get("toolbar"))
     this.prepend(toolbar)
     return toolbar
@@ -725,6 +736,37 @@ export class LexicalEditorElement extends HTMLElement {
     this.classList.toggle("lexxy-editor--empty", this.isEmpty)
   }
 
+  // Highlight is stored as color/background-color styles (plus the highlight format bit)
+  // on text nodes. The <mark> import conversion handles HTML, but content pasted from
+  // another Lexxy editor arrives as serialized nodes whose styles are restored directly —
+  // bypassing that conversion. This transform clears the highlight styling so a disabled
+  // highlight can never render in the editor, whatever path produced it.
+  #registerDisabledHighlightStripper(registered) {
+    if (this.supportsHighlight) return
+
+    registered.push(this.editor.registerNodeTransform(TextNode, (node) => {
+      if (node.hasFormat("highlight")) node.toggleFormat("highlight")
+
+      const styles = getStyleObjectFromCSS(node.getStyle())
+      if (styles.color || styles["background-color"]) {
+        delete styles.color
+        delete styles["background-color"]
+        node.setStyle(getCSSFromStyleObject(styles))
+      }
+    }))
+  }
+
+  // The highlight extension owns the <mark> import conversion, but Lexical's TextNode
+  // also imports <mark> as its built-in highlight format. When highlight is disabled the
+  // extension isn't registered, so drop the conversion entirely — highlighted markup is
+  // then reduced to plain text on every import path (initial value, setValue, paste) and
+  // <mark> is excluded from the sanitizer allow-list, which derives from these keys.
+  #removeDisabledConversions(editor) {
+    if (this.supportsHighlight) return
+
+    editor._htmlConversions?.delete("mark")
+  }
+
   #configureSanitizer(editor) {
     setSanitizerConfig(this.#getAllowedElements(editor))
   }
@@ -759,7 +801,7 @@ export class LexicalEditorElement extends HTMLElement {
         italic: { active: format.isItalic, enabled: true },
         strikethrough: { active: format.isStrikethrough, enabled: true },
         code: { active: format.isInCode, enabled: true },
-        highlight: { active: format.isHighlight, enabled: true },
+        highlight: { active: this.supportsHighlight && format.isHighlight, enabled: this.supportsHighlight },
         link: { active: format.isInLink, enabled: true },
         quote: { active: format.isInQuote, enabled: true },
         heading: { active: format.isInHeading, enabled: true },
@@ -770,7 +812,7 @@ export class LexicalEditorElement extends HTMLElement {
       }
 
       linkHref = linkNode ? linkNode.getURL() : null
-      highlight = format.isHighlight ? getHighlightStyles(selection) : null
+      highlight = this.supportsHighlight && format.isHighlight ? getHighlightStyles(selection) : null
       headingTag = format.headingTag ?? null
     })
 
@@ -804,6 +846,8 @@ export class LexicalEditorElement extends HTMLElement {
   }
 
   get #resolvedHighlightColors() {
+    if (!this.supportsHighlight) return null
+
     const buttons = this.config.get("highlight.buttons")
     if (!buttons) return null
 

src/extensions/highlight_extension.js

@@ -24,7 +24,7 @@ const pendingCodeHighlights = new WeakMap()
 
 export class HighlightExtension extends LexxyExtension {
   get enabled() {
-    return this.editorElement.supportsRichText
+    return this.editorElement.supportsHighlight
   }
 
   get lexicalExtension() {

src/extensions/trix_content_extension.js

@@ -13,24 +13,32 @@ export class TrixContentExtension extends LexxyExtension {
   }
 
   get lexicalExtension() {
+    // The em/span/strong/del converters below exist to import legacy Trix highlight
+    // colors. When highlight is disabled we drop the color application so those
+    // elements fall back to plain formatting (the em/span/strong handlers return null,
+    // deferring to Lexical's default bold/italic conversion; del keeps strikethrough).
+    const supportsHighlight = this.editorElement.supportsHighlight
+
     return defineExtension({
       name: "lexxy/trix-content",
       html: {
         import: {
-          em: (element) => onlyStyledElements(element, {
+          em: (element) => onlyStyledElements(element, supportsHighlight, {
             conversion: extendTextNodeConversion("i", $applyHighlightStyle),
             priority: 1
           }),
-          span: (element) => onlyStyledElements(element, {
+          span: (element) => onlyStyledElements(element, supportsHighlight, {
             conversion: extendTextNodeConversion("mark", $applyHighlightStyle),
             priority: 1
           }),
-          strong: (element) => onlyStyledElements(element, {
+          strong: (element) => onlyStyledElements(element, supportsHighlight, {
             conversion: extendTextNodeConversion("b", $applyHighlightStyle),
             priority: 1
           }),
           del: () => ({
-            conversion: extendTextNodeConversion("s", $applyStrikethrough, $applyHighlightStyle),
+            conversion: supportsHighlight
+              ? extendTextNodeConversion("s", $applyStrikethrough, $applyHighlightStyle)
+              : extendTextNodeConversion("s", $applyStrikethrough),
             priority: 1
           }),
           pre: (element) => onlyPreLanguageElements(element, {
@@ -43,7 +51,9 @@ export class TrixContentExtension extends LexxyExtension {
   }
 }
 
-function onlyStyledElements(element, conversion) {
+function onlyStyledElements(element, supportsHighlight, conversion) {
+  if (!supportsHighlight) return null
+
   const elementHighlighted = element.style.color !== "" || element.style.backgroundColor !== ""
   return elementHighlighted ? conversion : null
 }

test/browser/fixtures/highlight-false-bare.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <title>Lexxy Test — Highlight Disabled (bare boolean)</title>
+  <link rel="stylesheet" href="/styles.css">
+</head>
+<body>
+  <form>
+    <div class="title">
+      <input type="text" name="post[title]" placeholder="Post title" aria-label="Post title">
+    </div>
+
+    <div class="body">
+      <lexxy-editor class="lexxy-content" placeholder="Write something..." highlight="false" required></lexxy-editor>
+    </div>
+
+    <div class="events"></div>
+  </form>
+
+  <script type="module" src="/editor.js"></script>
+</body>
+</html>

test/browser/fixtures/highlight-false.html

@@ -0,0 +1,24 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+  <meta charset="utf-8">
+  <meta name="viewport" content="width=device-width,initial-scale=1">
+  <title>Lexxy Test — Highlight Disabled</title>
+  <link rel="stylesheet" href="/styles.css">
+</head>
+<body>
+  <form>
+    <div class="title">
+      <input type="text" name="post[title]" placeholder="Post title" aria-label="Post title">
+    </div>
+
+    <div class="body">
+      <lexxy-editor class="lexxy-content" placeholder="Write something..." highlight='{"enabled":false}' required></lexxy-editor>
+    </div>
+
+    <div class="events"></div>
+  </form>
+
+  <script type="module" src="/editor.js"></script>
+</body>
+</html>