Read initial editor value from HTML content

README.md

@@ -181,7 +181,18 @@ To populate a `<trix-editor>` with stored content, include that content in the a
 </form>
 ```
 
-Always use an associated input element to safely populate an editor. Trix won’t load any HTML content inside a `<trix-editor>…</trix-editor>` tag.
+Use an associated input element to initially populate an editor. When an associated input element is absent, Trix will safely sanitize then load any HTML content inside a `<trix-editor>…</trix-editor>` tag.
+
+```html
+<form …>
+  <trix-editor>Editor content goes here</trix-editor>
+</form>
+```
+
+> [!WARNING]
+> When a `<trix-editor>` element initially connects with both HTML content *and*
+> an associated input element, Trix will *always* disregard the HTML content and
+> load its initial content from the associated input element.
 
 ## Validating the Editor
 

action_text-trix/app/assets/javascripts/trix.js

@@ -13720,6 +13720,7 @@ $\
           triggerEvent("trix-before-initialize", {
             onElement: this
           });
+          this.defaultValue = this.inputElement ? this.inputElement.value : this.innerHTML;
           if (!this.hasAttribute("input") && this.parentNode && this.willCreateInput) {
             const inputId = "trix-input-".concat(this.trixId);
             this.setAttribute("input", inputId);
@@ -13731,7 +13732,7 @@ $\
           }
           this.editorController = new EditorController({
             editorElement: this,
-            html: this.defaultValue = this.value
+            html: this.defaultValue
           });
           requestAnimationFrame(() => triggerEvent("trix-initialize", {
             onElement: this

src/test/system/installation_process_test.js

@@ -1,6 +1,6 @@
 import EditorController from "trix/controllers/editor_controller"
 
-import { assert, test, testGroup } from "test/test_helper"
+import { assert, setFixtureHTML, test, testGroup } from "test/test_helper"
 import { nextFrame } from "../test_helpers/timing_helpers"
 
 testGroup("Installation process", { template: "editor_html" }, () => {
@@ -62,3 +62,38 @@ testGroup("Installation process with specified elements", { template: "editor_wi
     assert.equal(editorElement.value, "<div>Hello world</div>")
   })
 })
+
+testGroup("Installation process with content and without specified elements", () => {
+  test("loads the trix-editor element's innerHTML on boot", async () => {
+    await setFixtureHTML("<trix-editor><div>Hello world</div></trix-editor>")
+
+    const editorElement = getEditorElement()
+
+    assert.equal(1, editorElement.childElementCount, "sanitzes HTML")
+    assert.equal(editorElement.value, "<div>Hello world</div>")
+    assert.equal(editorElement.value, editorElement.inputElement.value)
+  })
+
+  test("sanitizes the trix-editor element's innerHTML on boot", async () => {
+    await setFixtureHTML("<trix-editor><script>alert('xss')</script></trix-editor>")
+
+    const editorElement = getEditorElement()
+
+    assert.equal(0, editorElement.querySelectorAll("script").length, "sanitzes HTML")
+    assert.equal(editorElement.value, "")
+    assert.equal(editorElement.value, editorElement.inputElement.value)
+  })
+})
+
+testGroup("Installation process with content and input", () => {
+  test("prioritzes loading its initial state from the input over the content", async () => {
+    await setFixtureHTML(`
+      <trix-editor input="input"><div>from editor</div></trix-editor>
+      <textarea id="input"><div>from input</div></textarea>
+    `)
+
+    const editorElement = getEditorElement()
+
+    assert.equal(editorElement.value, "<div>from input</div>")
+  })
+})

src/trix/elements/trix_editor_element.js

@@ -563,6 +563,7 @@ export default class TrixEditorElement extends HTMLElement {
 
       if (!this.editorController) {
         triggerEvent("trix-before-initialize", { onElement: this })
+        this.defaultValue = this.inputElement ? this.inputElement.value : this.innerHTML
         if (!this.hasAttribute("input") && this.parentNode && this.willCreateInput) {
           const inputId = `trix-input-${this.trixId}`
           this.setAttribute("input", inputId)
@@ -571,7 +572,7 @@ export default class TrixEditorElement extends HTMLElement {
         }
         this.editorController = new EditorController({
           editorElement: this,
-          html: this.defaultValue = this.value
+          html: this.defaultValue
         })
         requestAnimationFrame(() => triggerEvent("trix-initialize", { onElement: this }))
       }