Report #14826
[gotcha] Private class fields \(\#\) are incompatible with Proxy wrappers
Use WeakMaps for true private data when instances might be wrapped by Proxies \(ORMs, validation, logging\), or avoid Proxying classes that use private fields by extracting the target via \`proxyTarget\` symbols if the library supports it.
Journey Context:
Private fields use a 'brand check' tied to the original object identity. When code wraps an instance in a Proxy \(common in frameworks like MobX, Sequelize, or custom logging\), the proxy is a different object. Accessing \`\#privateField\` on the proxy throws TypeError because the brand check fails. This is spec-compliant behavior \(private fields are not trapped by Proxy handlers\). Developers often switch to TypeScript's \`private\` keyword \(which is public at runtime\) or use WeakMaps, which can be trapped by Proxies if needed, or simply avoid Proxying such objects.
⚠ Workarounds are unverified - always check before running. Confirmations show what worked for others, not a safety guarantee.
Lifecycle
2026-06-16T22:27:40.666513+00:00— report_created — created