Fix: duplicated newlines when using dictation on iOS 18+.

src/test/system/level_2_input_test.js

@@ -52,11 +52,18 @@ const performInputTypeUsingExecCommand = async (command, { inputType, data }) =>
 
   await nextFrame()
 
+  const isInsertParagraph = inputType === "insertParagraph"
+
   triggerInputEvent(document.activeElement, "beforeinput", { inputType, data })
-  document.execCommand(command, false, data)
-  assert.equal(inputEvents.length, 2)
+
+  // See `shouldRenderInmmediatelyToDealWithIOSDictation` to deal with iOS 18+ dictation bug.
+  if (!isInsertParagraph) {
+    document.execCommand(command, false, data)
+    assert.equal(inputEvents[1].type, "input")
+  }
+
+  assert.equal(inputEvents.length, isInsertParagraph ? 1 : 2)
   assert.equal(inputEvents[0].type, "beforeinput")
-  assert.equal(inputEvents[1].type, "input")
   assert.equal(inputEvents[0].inputType, inputType)
   assert.equal(inputEvents[0].data, data)
 

src/test/test_helpers/input_helpers.js

@@ -276,9 +276,8 @@ const simulateKeypress = async (keyName) => {
       await deleteInDirection("right")
       break
     case "return":
-      await nextFrame()
       triggerInputEvent(document.activeElement, "beforeinput", { inputType: "insertParagraph" })
-      await insertNode(document.createElement("br"))
+      break
   }
 }
 

src/trix/controllers/level_2_input_controller.js

@@ -1,4 +1,4 @@
-import { getAllAttributeNames, squishBreakableWhitespace } from "trix/core/helpers"
+import { getAllAttributeNames, shouldRenderInmmediatelyToDealWithIOSDictation, squishBreakableWhitespace } from "trix/core/helpers"
 import InputController from "trix/controllers/input_controller"
 import * as config from "trix/config"
 
@@ -73,14 +73,18 @@ export default class Level2InputController extends InputController {
     beforeinput(event) {
       const handler = this.constructor.inputTypes[event.inputType]
 
-      // Handles bug with Siri dictation on iOS 18+.
-      if (!event.inputType) {
-        this.render()
-      }
+      const immmediateRender = shouldRenderInmmediatelyToDealWithIOSDictation(event)
 
       if (handler) {
         this.withEvent(event, handler)
-        this.scheduleRender()
+
+        if (!immmediateRender) {
+          this.scheduleRender()
+        }
+      }
+
+      if (immmediateRender) {
+        this.render()
       }
     },
 

src/trix/core/helpers/events.js

@@ -43,3 +43,17 @@ export const keyEventIsKeyboardCommand = (function() {
     return (event) => event.ctrlKey
   }
 })()
+
+export function shouldRenderInmmediatelyToDealWithIOSDictation(inputEvent) {
+  if (/iPhone|iPad/.test(navigator.userAgent)) {
+    // Handle garbled content and duplicated newlines when using dictation on iOS 18+. Upon dictation completion, iOS sends
+    // the list of insertText / insertParagraph events in a quick sequence. If we don't render
+    // the editor synchronously, the internal range fails to update and results in garbled content or duplicated newlines.
+    //
+    // This workaround is necessary because iOS doesn't send composing events as expected while dictating:
+    // https://bugs.webkit.org/show_bug.cgi?id=261764
+    return !inputEvent.inputType || inputEvent.inputType === "insertParagraph"
+  } else {
+    return false
+  }
+}