CLAUDE WATERMARK REMOVER · DESTINATION TEST
Why does a cloned date support methods while its JSON round trip does not?
structuredClone retains a Date; JSON.parse returns an ISO string.
What the test establishes
Both routes preserve the displayed instant in this fixture, but only one preserves the JavaScript Date type. A destination that calls date methods must validate the post-transfer type rather than accept a familiar ISO preview as proof. Textual JSON is useful for interchange when the receiving schema explicitly rebuilds dates. A structured clone serves a different local contract. The experiment uses an explicit UTC suffix and a valid timestamp to remove timezone ambiguity from the type comparison. Cleanup supplies the timestamp string; parsing, cloning and serialization are separate operations that the application must handle deliberately.
Reproduce the observation
Save tested-app.js and reproduce.cjs together, then run node reproduce.cjs. Compare its output with the recorded observation. The harness executes the actual homepage callback in a minimal DOM and records its resulting field values and method calls. Destination operations run in Node.js; the homepage DOM is a controlled substitute. Runtime: v24.22.1. No submitted text or genuine Claude output is used.
{
"cloneIsDate": true,
"cloneISO": "2026-11-05T00:00:00.000Z",
"jsonType": "string",
"jsonValue": "2026-11-05T00:00:00.000Z"
}Capability boundary
One valid UTC instant is measured. Invalid dates and timezone display are excluded.
This Claude watermark remover edits a small selected character set. These callback observations do not establish authorship, detector scores, statistical-watermark removal or end-to-end browser behavior. For real work, keep the original and compare the exact result at its destination.
Primary material and next step
The tested first-party source snapshot and complete harness are the primary material for this page. For broader scope, read invisible Unicode versus AI watermarks, or return to the cleaner.