Fix serialization and mutation of <textarea> elements (#1351)

* Fix serialization and mutation of <textarea> elements taking account the duality that the value can be set in either the child node, or in the value _parameter_ (not attribute)

* Backwards compatibility: Bug fix and regression test for #112
 - this is to fix up 'historical' recordings, as duplicate textarea content should no longer be being created at record time
 - new test shows what the snapshot generated by previous versions of rrweb used to look like, hence 'bad'
 - original 0efe23f04a fix either didn't work or no longer works due to childNodes being appended subsequent to this part of the code
 - during review, we also verified that the `_cssText` case should still be handled okay, as there's currently no scenario where csstext is present with css child nodes of a <style>

* Masking: Fix that textarea values were being missed by the masking system if the value was recorded as a child node
 - I didn't notice that form.html was used in other tests, so lucky that I noticed that those tests also should have the 'pre value' masked out

* Simplify by always storing the textarea value in the `.value` attribute (from it's DOM property) and not as a childNode. It should still be rebuilt as a childNode rather than a property
---------

Authored-by: eoghanmurray <eoghan@getthere.ie>

.changeset/rare-adults-sneeze.md

@@ -0,0 +1,6 @@
+---
+'rrweb-snapshot': patch
+'rrweb': patch
+---
+
+Don't double-record the values of <textarea>s when they already have some content prefilled #1301

packages/rrweb-snapshot/package.json

@@ -5,7 +5,8 @@
   "scripts": {
     "prepare": "npm run prepack",
     "prepack": "npm run bundle && npm run typings",
-    "test": "jest",
+    "retest": "jest",
+    "test": "yarn bundle && yarn retest",
     "test:watch": "jest --watch",
     "test:update": "jest --updateSnapshot",
     "bundle": "rollup --config",

packages/rrweb-snapshot/src/rebuild.ts

@@ -5,7 +5,6 @@ import {
   tagMap,
   elementNode,
   BuildCache,
-  attributes,
   legacyAttributes,
 } from './types';
 import { isElement, Mirror, isNodeMetaEqual } from './utils';
@@ -200,14 +199,9 @@ function buildNode(
           value = addHoverClass(value, cache);
         }
         if ((isTextarea || isRemoteOrDynamicCss) && typeof value === 'string') {
-          const child = doc.createTextNode(value);
+          node.appendChild(doc.createTextNode(value));
           // https://github.com/rrweb-io/rrweb/issues/112
-          for (const c of Array.from(node.childNodes)) {
+          n.childNodes = []; // value overrides childNodes
-            if (c.nodeType === node.TEXT_NODE) {
-              node.removeChild(c);
-            }
-          }
-          node.appendChild(child);
           continue;
         }
 

packages/rrweb-snapshot/src/snapshot.ts

@@ -10,6 +10,7 @@ import {
   MaskInputFn,
   KeepIframeSrcFn,
   ICanvas,
+  elementNode,
   serializedElementNodeWithId,
 } from './types';
 import {
@@ -672,10 +673,9 @@ function serializeElementNode(
       attributes.type !== 'button' &&
       value
     ) {
-      const type = getInputType(n);
       attributes.value = maskInputValue({
         element: n,
-        type,
+        type: getInputType(n),
         tagName,
         value,
         maskInputOptions,
@@ -1090,10 +1090,19 @@ export function serializeNodeWithId(
       stylesheetLoadTimeout,
       keepIframeSrcFn,
     };
-    for (const childN of Array.from(n.childNodes)) {
+
-      const serializedChildNode = serializeNodeWithId(childN, bypassOptions);
+    if (
-      if (serializedChildNode) {
+      serializedNode.type === NodeType.Element &&
-        serializedNode.childNodes.push(serializedChildNode);
+      serializedNode.tagName === 'textarea' &&
+      (serializedNode as elementNode).attributes.value !== undefined
+    ) {
+      // value parameter in DOM reflects the correct value, so ignore childNode
+    } else {
+      for (const childN of Array.from(n.childNodes)) {
+        const serializedChildNode = serializeNodeWithId(childN, bypassOptions);
+        if (serializedChildNode) {
+          serializedNode.childNodes.push(serializedChildNode);
+        }
       }
     }
 

packages/rrweb-snapshot/test/__snapshots__/integration.test.ts.snap

@@ -247,6 +247,7 @@ exports[`integration tests [html file]: form-fields.html 1`] = `
       </label>
       <label for=\\"textarea\\">
         <textarea name=\\"\\" id=\\"\\" cols=\\"30\\" rows=\\"10\\">1234</textarea>
+        <textarea name=\\"\\" id=\\"\\" cols=\\"30\\" rows=\\"10\\">1234</textarea>
       </label>
       <label for=\\"select\\">
         <select name=\\"\\" id=\\"\\" value=\\"2\\">

packages/rrweb-snapshot/test/html/form-fields.html

@@ -20,6 +20,7 @@
       </label>
       <label for="textarea">
         <textarea name="" id="" cols="30" rows="10"></textarea>
+        <textarea name="" id="" cols="30" rows="10">-1</textarea>
       </label>
       <label for="select">
         <select name="" id="">
@@ -36,7 +37,8 @@
     document.querySelector('input[type="text"]').value = '1';
     document.querySelector('input[type="radio"]').checked = true;
     document.querySelector('input[type="checkbox"]').checked = true;
-    document.querySelector('textarea').value = '1234';
+    document.querySelector('textarea:empty').value = '1234';
+    document.querySelector('textarea:not(:empty)').value = '1234';
     document.querySelector('select').value = '2';
   </script>
 </html>

packages/rrweb-snapshot/test/snapshot.test.ts

@@ -7,7 +7,7 @@ import {
   serializeNodeWithId,
   _isBlockedElement,
 } from '../src/snapshot';
-import { serializedNodeWithId } from '../src/types';
+import { serializedNodeWithId, elementNode } from '../src/types';
 import { Mirror } from '../src/utils';
 
 describe('absolute url to stylesheet', () => {
@@ -218,3 +218,42 @@ describe('scrollTop/scrollLeft', () => {
     });
   });
 });
+
+describe('form', () => {
+  const serializeNode = (node: Node): serializedNodeWithId | null => {
+    return serializeNodeWithId(node, {
+      doc: document,
+      mirror: new Mirror(),
+      blockClass: 'blockblock',
+      blockSelector: null,
+      maskTextClass: 'maskmask',
+      maskTextSelector: null,
+      skipChild: false,
+      inlineStylesheet: true,
+      maskTextFn: undefined,
+      maskInputFn: undefined,
+      slimDOMOptions: {},
+      newlyAddedElement: false,
+    });
+  };
+
+  const render = (html: string): HTMLTextAreaElement => {
+    document.write(html);
+    return document.querySelector('textarea')!;
+  };
+
+  it('should record textarea values once', () => {
+    const el = render(`<textarea>Lorem ipsum</textarea>`);
+    const sel = serializeNode(el) as elementNode;
+
+    // we serialize according to where the DOM stores the value, not how
+    // the HTML stores it (this is so that maskInputValue can work over
+    // inputs/textareas/selects in a uniform way)
+    expect(sel).toMatchObject({
+      attributes: {
+        value: 'Lorem ipsum',
+      },
+    });
+    expect(sel?.childNodes).toEqual([]); // shouldn't be stored in childNodes while in transit
+  });
+});

packages/rrweb/package.json

@@ -12,6 +12,7 @@
     "test": "yarn test:headless",
     "test:watch": "yarn test:headless -- --watch",
     "test:update": "yarn test:headless -- --updateSnapshot",
+    "retest:update": "PUPPETEER_HEADLESS=true yarn retest -- --updateSnapshot",
     "repl": "yarn bundle:browser && node scripts/repl.js",
     "live-stream": "yarn bundle:browser && node scripts/stream.js",
     "dev": "yarn bundle:browser --watch",

packages/rrweb/src/record/mutation.ts

@@ -285,7 +285,11 @@ export default class MutationBuffer {
       return nextId;
     };
     const pushAdd = (n: Node) => {
-      if (!n.parentNode || !inDom(n)) {
+      if (
+        !n.parentNode ||
+        !inDom(n) ||
+        (n.parentNode as Element).tagName === 'TEXTAREA'
+      ) {
         return;
       }
       const parentId = isShadowRoot(n.parentNode)
@@ -435,10 +439,17 @@ export default class MutationBuffer {
 
     const payload = {
       texts: this.texts
-        .map((text) => ({
+        .map((text) => {
-          id: this.mirror.getId(text.node),
+          const n = text.node;
-          value: text.value,
+          if ((n.parentNode as Element).tagName === 'TEXTAREA') {
-        }))
+            // the node is being ignored as it isn't in the mirror, so shift mutation to attributes on parent textarea
+            this.genTextAreaValueMutation(n.parentNode as HTMLTextAreaElement);
+          }
+          return {
+            id: this.mirror.getId(n),
+            value: text.value,
+          };
+        })
         // no need to include them on added elements, as they have just been serialized with up to date attribubtes
         .filter((text) => !addedIds.has(text.id))
         // text mutation's id was not in the mirror map means the target node has been removed
@@ -497,6 +508,24 @@ export default class MutationBuffer {
     this.mutationCb(payload);
   };
 
+  private genTextAreaValueMutation = (textarea: HTMLTextAreaElement) => {
+    let item = this.attributeMap.get(textarea);
+    if (!item) {
+      item = {
+        node: textarea,
+        attributes: {},
+        styleDiff: {},
+        _unchangedStyles: {},
+      };
+      this.attributes.push(item);
+      this.attributeMap.set(textarea, item);
+    }
+    item.attributes.value = Array.from(
+      textarea.childNodes,
+      (cn) => cn.textContent || '',
+    ).join('');
+  };
+
   private processMutation = (m: mutationRecord) => {
     if (isIgnored(m.target, this.mirror)) {
       return;
@@ -642,6 +671,12 @@ export default class MutationBuffer {
         if (isBlocked(m.target, this.blockClass, this.blockSelector, true))
           return;
 
+        if ((m.target as Element).tagName === 'TEXTAREA') {
+          // children would be ignored in genAdds as they aren't in the mirror
+          this.genTextAreaValueMutation(m.target as HTMLTextAreaElement);
+          return; // any removedNodes won't have been in mirror either
+        }
+
         m.addedNodes.forEach((n) => this.genAdds(n, m.target));
         m.removedNodes.forEach((n) => {
           const nodeId = this.mirror.getId(n);

packages/rrweb/src/replay/index.ts

@@ -1564,6 +1564,8 @@ export class Replayer {
         const childNodeArray = Array.isArray(parent.childNodes)
           ? parent.childNodes
           : Array.from(parent.childNodes);
+        // This should be redundant now as we are either recording the value or the childNode, and not both
+        // keeping around for backwards compatibility with old bad double data, see
 
         // https://github.com/rrweb-io/rrweb/issues/745
         // parent is textarea, will only keep one child node as the value
@@ -1761,10 +1763,24 @@ export class Replayer {
                   // for safe
                 }
               }
-              (target as Element | RRElement).setAttribute(
+              if (attributeName === 'value' && target.nodeName === 'TEXTAREA') {
-                attributeName,
+                // this may or may not have an effect on the value property (which is what is displayed)
-                value,
+                // depending on whether the textarea has been modified by the user yet
-              );
+                // TODO: replaceChildNodes is not available in RRDom
+                const textarea = target as TNode;
+                textarea.childNodes.forEach((c) =>
+                  textarea.removeChild(c as TNode),
+                );
+                const tn = target.ownerDocument?.createTextNode(value);
+                if (tn) {
+                  textarea.appendChild(tn as TNode);
+                }
+              } else {
+                (target as Element | RRElement).setAttribute(
+                  attributeName,
+                  value,
+                );
+              }
             } catch (error) {
               this.warn(
                 'An error occurred may due to the checkout feature.',

packages/rrweb/test/__snapshots__/integration.test.ts.snap

@@ -2268,8 +2268,22 @@ exports[`record integration tests can record form interactions 1`] = `
                       },
                       {
                         \\"type\\": 3,
-                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"textContent\\": \\"\\\\n      \\",
                         \\"id\\": 61
+                      },
+                      {
+                        \\"type\\": 2,
+                        \\"tagName\\": \\"textarea\\",
+                        \\"attributes\\": {
+                          \\"value\\": \\"pre value\\"
+                        },
+                        \\"childNodes\\": [],
+                        \\"id\\": 62
+                      },
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 63
                       }
                     ],
                     \\"id\\": 18
@@ -2277,7 +2291,7 @@ exports[`record integration tests can record form interactions 1`] = `
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n  \\\\n    \\",
-                    \\"id\\": 62
+                    \\"id\\": 64
                   },
                   {
                     \\"type\\": 2,
@@ -2287,15 +2301,15 @@ exports[`record integration tests can record form interactions 1`] = `
                       {
                         \\"type\\": 3,
                         \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
-                        \\"id\\": 64
+                        \\"id\\": 66
                       }
                     ],
-                    \\"id\\": 63
+                    \\"id\\": 65
                   },
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
-                    \\"id\\": 65
+                    \\"id\\": 67
                   }
                 ],
                 \\"id\\": 16
@@ -3811,6 +3825,270 @@ exports[`record integration tests can record style changes compactly and preserv
 ]"
 `;
 
+exports[`record integration tests can record textarea mutations correctly 1`] = `
+"[
+  {
+    \\"type\\": 0,
+    \\"data\\": {}
+  },
+  {
+    \\"type\\": 1,
+    \\"data\\": {}
+  },
+  {
+    \\"type\\": 4,
+    \\"data\\": {
+      \\"href\\": \\"about:blank\\",
+      \\"width\\": 1920,
+      \\"height\\": 1080
+    }
+  },
+  {
+    \\"type\\": 2,
+    \\"data\\": {
+      \\"node\\": {
+        \\"type\\": 0,
+        \\"childNodes\\": [
+          {
+            \\"type\\": 1,
+            \\"name\\": \\"html\\",
+            \\"publicId\\": \\"\\",
+            \\"systemId\\": \\"\\",
+            \\"id\\": 2
+          },
+          {
+            \\"type\\": 2,
+            \\"tagName\\": \\"html\\",
+            \\"attributes\\": {
+              \\"lang\\": \\"en\\"
+            },
+            \\"childNodes\\": [
+              {
+                \\"type\\": 2,
+                \\"tagName\\": \\"head\\",
+                \\"attributes\\": {},
+                \\"childNodes\\": [
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 5
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"meta\\",
+                    \\"attributes\\": {
+                      \\"charset\\": \\"UTF-8\\"
+                    },
+                    \\"childNodes\\": [],
+                    \\"id\\": 6
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 7
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"meta\\",
+                    \\"attributes\\": {
+                      \\"name\\": \\"viewport\\",
+                      \\"content\\": \\"width=device-width, initial-scale=1.0\\"
+                    },
+                    \\"childNodes\\": [],
+                    \\"id\\": 8
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 9
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"title\\",
+                    \\"attributes\\": {},
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"Empty\\",
+                        \\"id\\": 11
+                      }
+                    ],
+                    \\"id\\": 10
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n  \\",
+                    \\"id\\": 12
+                  }
+                ],
+                \\"id\\": 4
+              },
+              {
+                \\"type\\": 3,
+                \\"textContent\\": \\"\\\\n  \\",
+                \\"id\\": 13
+              },
+              {
+                \\"type\\": 2,
+                \\"tagName\\": \\"body\\",
+                \\"attributes\\": {},
+                \\"childNodes\\": [
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\",
+                    \\"id\\": 15
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"div\\",
+                    \\"attributes\\": {
+                      \\"id\\": \\"one\\"
+                    },
+                    \\"childNodes\\": [],
+                    \\"id\\": 16
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n  \\\\n    \\",
+                    \\"id\\": 17
+                  },
+                  {
+                    \\"type\\": 2,
+                    \\"tagName\\": \\"script\\",
+                    \\"attributes\\": {},
+                    \\"childNodes\\": [
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
+                        \\"id\\": 19
+                      }
+                    ],
+                    \\"id\\": 18
+                  },
+                  {
+                    \\"type\\": 3,
+                    \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
+                    \\"id\\": 20
+                  }
+                ],
+                \\"id\\": 14
+              }
+            ],
+            \\"id\\": 3
+          }
+        ],
+        \\"id\\": 1
+      },
+      \\"initialOffset\\": {
+        \\"left\\": 0,
+        \\"top\\": 0
+      }
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 0,
+      \\"texts\\": [],
+      \\"attributes\\": [],
+      \\"removes\\": [],
+      \\"adds\\": [
+        {
+          \\"parentId\\": 14,
+          \\"nextId\\": null,
+          \\"node\\": {
+            \\"type\\": 2,
+            \\"tagName\\": \\"textarea\\",
+            \\"attributes\\": {
+              \\"value\\": \\"pre value\\"
+            },
+            \\"childNodes\\": [],
+            \\"id\\": 21
+          }
+        }
+      ]
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 0,
+      \\"texts\\": [],
+      \\"attributes\\": [
+        {
+          \\"id\\": 21,
+          \\"attributes\\": {
+            \\"value\\": \\"ok\\"
+          }
+        }
+      ],
+      \\"removes\\": [],
+      \\"adds\\": []
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 0,
+      \\"texts\\": [],
+      \\"attributes\\": [
+        {
+          \\"id\\": 21,
+          \\"attributes\\": {
+            \\"value\\": \\"ok3\\"
+          }
+        }
+      ],
+      \\"removes\\": [],
+      \\"adds\\": []
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 2,
+      \\"type\\": 5,
+      \\"id\\": 21
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 5,
+      \\"text\\": \\"1ok3\\",
+      \\"isChecked\\": false,
+      \\"id\\": 21
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 0,
+      \\"texts\\": [],
+      \\"attributes\\": [
+        {
+          \\"id\\": 21,
+          \\"attributes\\": {
+            \\"value\\": \\"ignore\\"
+          }
+        }
+      ],
+      \\"removes\\": [],
+      \\"adds\\": []
+    }
+  },
+  {
+    \\"type\\": 3,
+    \\"data\\": {
+      \\"source\\": 5,
+      \\"text\\": \\"12ok3\\",
+      \\"isChecked\\": false,
+      \\"id\\": 21
+    }
+  }
+]"
+`;
+
 exports[`record integration tests can use maskInputOptions to configure which type of inputs should be masked 1`] = `
 "[
   {
@@ -4238,8 +4516,22 @@ exports[`record integration tests can use maskInputOptions to configure which ty
                       },
                       {
                         \\"type\\": 3,
-                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"textContent\\": \\"\\\\n      \\",
                         \\"id\\": 61
+                      },
+                      {
+                        \\"type\\": 2,
+                        \\"tagName\\": \\"textarea\\",
+                        \\"attributes\\": {
+                          \\"value\\": \\"pre value\\"
+                        },
+                        \\"childNodes\\": [],
+                        \\"id\\": 62
+                      },
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 63
                       }
                     ],
                     \\"id\\": 18
@@ -4247,7 +4539,7 @@ exports[`record integration tests can use maskInputOptions to configure which ty
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n  \\\\n    \\",
-                    \\"id\\": 62
+                    \\"id\\": 64
                   },
                   {
                     \\"type\\": 2,
@@ -4257,15 +4549,15 @@ exports[`record integration tests can use maskInputOptions to configure which ty
                       {
                         \\"type\\": 3,
                         \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
-                        \\"id\\": 64
+                        \\"id\\": 66
                       }
                     ],
-                    \\"id\\": 63
+                    \\"id\\": 65
                   },
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
-                    \\"id\\": 65
+                    \\"id\\": 67
                   }
                 ],
                 \\"id\\": 16
@@ -6230,8 +6522,22 @@ exports[`record integration tests should mask inputs via function call 1`] = `
                       },
                       {
                         \\"type\\": 3,
-                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"textContent\\": \\"\\\\n      \\",
                         \\"id\\": 61
+                      },
+                      {
+                        \\"type\\": 2,
+                        \\"tagName\\": \\"textarea\\",
+                        \\"attributes\\": {
+                          \\"value\\": \\"*********\\"
+                        },
+                        \\"childNodes\\": [],
+                        \\"id\\": 62
+                      },
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 63
                       }
                     ],
                     \\"id\\": 18
@@ -6239,7 +6545,7 @@ exports[`record integration tests should mask inputs via function call 1`] = `
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n  \\\\n    \\",
-                    \\"id\\": 62
+                    \\"id\\": 64
                   },
                   {
                     \\"type\\": 2,
@@ -6249,15 +6555,15 @@ exports[`record integration tests should mask inputs via function call 1`] = `
                       {
                         \\"type\\": 3,
                         \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
-                        \\"id\\": 64
+                        \\"id\\": 66
                       }
                     ],
-                    \\"id\\": 63
+                    \\"id\\": 65
                   },
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
-                    \\"id\\": 65
+                    \\"id\\": 67
                   }
                 ],
                 \\"id\\": 16
@@ -9917,8 +10223,22 @@ exports[`record integration tests should not record input values if maskAllInput
                       },
                       {
                         \\"type\\": 3,
-                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"textContent\\": \\"\\\\n      \\",
                         \\"id\\": 61
+                      },
+                      {
+                        \\"type\\": 2,
+                        \\"tagName\\": \\"textarea\\",
+                        \\"attributes\\": {
+                          \\"value\\": \\"*********\\"
+                        },
+                        \\"childNodes\\": [],
+                        \\"id\\": 62
+                      },
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 63
                       }
                     ],
                     \\"id\\": 18
@@ -9926,7 +10246,7 @@ exports[`record integration tests should not record input values if maskAllInput
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n  \\\\n    \\",
-                    \\"id\\": 62
+                    \\"id\\": 64
                   },
                   {
                     \\"type\\": 2,
@@ -9936,15 +10256,15 @@ exports[`record integration tests should not record input values if maskAllInput
                       {
                         \\"type\\": 3,
                         \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
-                        \\"id\\": 64
+                        \\"id\\": 66
                       }
                     ],
-                    \\"id\\": 63
+                    \\"id\\": 65
                   },
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
-                    \\"id\\": 65
+                    \\"id\\": 67
                   }
                 ],
                 \\"id\\": 16
@@ -13626,8 +13946,22 @@ exports[`record integration tests should record input userTriggered values if us
                       },
                       {
                         \\"type\\": 3,
-                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"textContent\\": \\"\\\\n      \\",
                         \\"id\\": 61
+                      },
+                      {
+                        \\"type\\": 2,
+                        \\"tagName\\": \\"textarea\\",
+                        \\"attributes\\": {
+                          \\"value\\": \\"pre value\\"
+                        },
+                        \\"childNodes\\": [],
+                        \\"id\\": 62
+                      },
+                      {
+                        \\"type\\": 3,
+                        \\"textContent\\": \\"\\\\n    \\",
+                        \\"id\\": 63
                       }
                     ],
                     \\"id\\": 18
@@ -13635,7 +13969,7 @@ exports[`record integration tests should record input userTriggered values if us
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n  \\\\n    \\",
-                    \\"id\\": 62
+                    \\"id\\": 64
                   },
                   {
                     \\"type\\": 2,
@@ -13645,15 +13979,15 @@ exports[`record integration tests should record input userTriggered values if us
                       {
                         \\"type\\": 3,
                         \\"textContent\\": \\"SCRIPT_PLACEHOLDER\\",
-                        \\"id\\": 64
+                        \\"id\\": 66
                       }
                     ],
-                    \\"id\\": 63
+                    \\"id\\": 65
                   },
                   {
                     \\"type\\": 3,
                     \\"textContent\\": \\"\\\\n    \\\\n    \\\\n\\\\n\\",
-                    \\"id\\": 65
+                    \\"id\\": 67
                   }
                 ],
                 \\"id\\": 16

packages/rrweb/test/events/bad-textarea.ts

@@ -0,0 +1,81 @@
+import { EventType, IncrementalSource } from '@rrweb/types';
+import type { eventWithTime } from '@rrweb/types';
+
+const now = Date.now();
+const events: eventWithTime[] = [
+  {
+    type: EventType.DomContentLoaded,
+    data: {},
+    timestamp: now,
+  },
+  {
+    type: EventType.Load,
+    data: {},
+    timestamp: now + 50,
+  },
+  {
+    type: EventType.Meta,
+    data: {
+      href: 'http://localhost',
+      width: 1000,
+      height: 800,
+    },
+    timestamp: now + 50,
+  },
+  // full snapshot:
+  {
+    data: {
+      node: {
+        id: 1,
+        type: 0,
+        childNodes: [
+          { id: 2, name: 'html', type: 1, publicId: '', systemId: '' },
+          {
+            id: 3,
+            type: 2,
+            tagName: 'html',
+            attributes: { lang: 'en' },
+            childNodes: [
+              {
+                id: 4,
+                type: 2,
+                tagName: 'head',
+                attributes: {},
+                childNodes: [],
+              },
+              {
+                id: 5,
+                type: 2,
+                tagName: 'body',
+                attributes: {},
+                childNodes: [
+                  {
+                    id: 6,
+                    type: 2,
+                    tagName: 'textarea',
+                    attributes: {
+                      value: 'this value is used for replay',
+                    },
+                    childNodes: [
+                      {
+                        type: 3,
+                        textContent:
+                          'this value is IGNORED for replay (but was present as a duplicte in legacy recordings)',
+                        id: 7,
+                      },
+                    ],
+                  },
+                ],
+              },
+            ],
+          },
+        ],
+      },
+      initialOffset: { top: 0, left: 0 },
+    },
+    type: EventType.FullSnapshot,
+    timestamp: now + 50,
+  },
+];
+
+export default events;

packages/rrweb/test/html/form.html

@@ -33,6 +33,7 @@
       <label for="password">
         <input type="password" />
       </label>
+      <textarea>pre value</textarea>
     </form>
   </body>
 </html>

packages/rrweb/test/integration.test.ts

@@ -105,6 +105,69 @@ describe('record integration tests', function (this: ISuite) {
     assertSnapshot(snapshots);
   });
 
+  it('can record textarea mutations correctly', async () => {
+    const page: puppeteer.Page = await browser.newPage();
+    await page.goto('about:blank');
+    await page.setContent(getHtml.call(this, 'empty.html'));
+
+    await waitForRAF(page); // ensure mutations aren't included in fullsnapshot
+
+    await page.evaluate(() => {
+      const ta = document.createElement('textarea');
+      ta.innerText = 'pre value';
+      document.body.append(ta);
+    });
+    await page.evaluate(() => {
+      const t = document.querySelector('textarea') as HTMLTextAreaElement;
+      t.innerText = 'ok'; // this mutation should be recorded
+    });
+    await page.evaluate(() => {
+      const t = document.querySelector('textarea') as HTMLTextAreaElement;
+      (t.childNodes[0] as Text).appendData('3'); // this mutation is also valid
+    });
+
+    await page.type('textarea', '1'); // types (inserts) at index 0, in front of existing text
+
+    await page.evaluate(() => {
+      const t = document.querySelector('textarea') as HTMLTextAreaElement;
+      // user has typed so childNode content should now be ignored
+      (t.childNodes[0] as Text).data = 'igno';
+      (t.childNodes[0] as Text).appendData('re');
+      // this mutation is currently emitted, and shows up in snapshot
+      // but we will check that it doesn't have any effect on the value
+      // there is nothing explicit in rrweb which enforces this, but this test may protect against
+      // a future change where a mutation on a textarea incorrectly updates the .value
+    });
+
+    await page.type('textarea', '2'); // cursor is at index 1
+
+    const snapshots = (await page.evaluate(
+      'window.snapshots',
+    )) as eventWithTime[];
+    assertSnapshot(snapshots);
+
+    // check after each mutation and text input
+    const replayTextareaValues = await page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(window.snapshots);
+      const vals = [];
+      window.snapshots.filter((e)=>e.data.attributes || e.data.source === 5).forEach((e)=>{
+        replayer.pause((e.timestamp - window.snapshots[0].timestamp)+1);
+        let ts = replayer.iframe.contentDocument.querySelector('textarea');
+        vals.push((e.data.source === 0 ? 'Mutation' : 'User') + ':' + ts.value);
+      });
+      vals;
+    `);
+    expect(replayTextareaValues).toEqual([
+      'Mutation:pre value',
+      'Mutation:ok',
+      'Mutation:ok3',
+      'User:1ok3',
+      'Mutation:1ok3', // if this gets set to 'ignore', it's an error, as the 'user' has modified the textarea
+      'User:12ok3',
+    ]);
+  });
+
   it('can record childList mutations', async () => {
     const page: puppeteer.Page = await browser.newPage();
     await page.goto('about:blank');

packages/rrweb/test/record/__snapshots__/cross-origin-iframes.test.ts.snap

@@ -1586,9 +1586,25 @@ exports[`cross origin iframes form.html should map input events correctly 1`] =
                           },
                           {
                             \\"type\\": 3,
-                            \\"textContent\\": \\"\\\\n    \\",
+                            \\"textContent\\": \\"\\\\n      \\",
                             \\"rootId\\": 11,
                             \\"id\\": 73
+                          },
+                          {
+                            \\"type\\": 2,
+                            \\"tagName\\": \\"textarea\\",
+                            \\"attributes\\": {
+                              \\"value\\": \\"pre value\\"
+                            },
+                            \\"childNodes\\": [],
+                            \\"rootId\\": 11,
+                            \\"id\\": 74
+                          },
+                          {
+                            \\"type\\": 3,
+                            \\"textContent\\": \\"\\\\n    \\",
+                            \\"rootId\\": 11,
+                            \\"id\\": 75
                           }
                         ],
                         \\"rootId\\": 11,
@@ -1598,7 +1614,7 @@ exports[`cross origin iframes form.html should map input events correctly 1`] =
                         \\"type\\": 3,
                         \\"textContent\\": \\"\\\\n  \\\\n\\\\n\\",
                         \\"rootId\\": 11,
-                        \\"id\\": 74
+                        \\"id\\": 76
                       }
                     ],
                     \\"rootId\\": 11,
@@ -2583,9 +2599,25 @@ exports[`cross origin iframes form.html should map scroll events correctly 1`] =
                           },
                           {
                             \\"type\\": 3,
-                            \\"textContent\\": \\"\\\\n    \\",
+                            \\"textContent\\": \\"\\\\n      \\",
                             \\"rootId\\": 11,
                             \\"id\\": 73
+                          },
+                          {
+                            \\"type\\": 2,
+                            \\"tagName\\": \\"textarea\\",
+                            \\"attributes\\": {
+                              \\"value\\": \\"pre value\\"
+                            },
+                            \\"childNodes\\": [],
+                            \\"rootId\\": 11,
+                            \\"id\\": 74
+                          },
+                          {
+                            \\"type\\": 3,
+                            \\"textContent\\": \\"\\\\n    \\",
+                            \\"rootId\\": 11,
+                            \\"id\\": 75
                           }
                         ],
                         \\"rootId\\": 11,
@@ -2595,7 +2627,7 @@ exports[`cross origin iframes form.html should map scroll events correctly 1`] =
                         \\"type\\": 3,
                         \\"textContent\\": \\"\\\\n  \\\\n\\\\n\\",
                         \\"rootId\\": 11,
-                        \\"id\\": 74
+                        \\"id\\": 76
                       }
                     ],
                     \\"rootId\\": 11,

packages/rrweb/test/replayer.test.ts

@@ -16,6 +16,7 @@ import inputEvents from './events/input';
 import iframeEvents from './events/iframe';
 import selectionEvents from './events/selection';
 import shadowDomEvents from './events/shadow-dom';
+import textareaEvents from './events/bad-textarea';
 import StyleSheetTextMutation from './events/style-sheet-text-mutation';
 import canvasInIframe from './events/canvas-in-iframe';
 import adoptedStyleSheet from './events/adopted-style-sheet';
@@ -1092,4 +1093,19 @@ describe('replayer', function () {
     // If the custom element is defined, the display value will be 'block'.
     expect(displayValue).toEqual('block');
   });
+
+  it('can deal with legacy duplicate/conflicting values on textareas', async () => {
+    await page.evaluate(`events = ${JSON.stringify(textareaEvents)}`);
+
+    const displayValue = await page.evaluate(`
+      const { Replayer } = rrweb;
+      const replayer = new Replayer(events);
+      replayer.pause(100);
+      const textarea = replayer.iframe.contentDocument.querySelector('textarea');
+      textarea.value;
+    `);
+    // If the custom element is not defined, the display value will be 'none'.
+    // If the custom element is defined, the display value will be 'block'.
+    expect(displayValue).toEqual('this value is used for replay');
+  });
 });