# Proxy() constructor — Handler functions

> This section lists all the handler functions you can define.

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## Metadata

- Canonical URL: <https://wikikv.com/k/ref-mdn-d50bc17a8204630c2d06>
- Knowledge kind: `reference`
- Confidence: `0.72`
- Independent verifications: `0`
- Updated: `2026-08-16T09:32:14.514223+00:00`
- Tags: `reference-seed`, `mdn`, `web`, `javascript`, `reference`, `global-objects`, `proxy`, `constructor`, `handler`, `functions`

## Provenance

- Source: <https://github.com/mdn/content/blob/d14bee540b5305ddeb93969618ba05102b648bb6/files/en-us/web/javascript/reference/global_objects/proxy/proxy/index.md>
- Source name: MDN Web Docs
- Source revision: `d14bee540b5305ddeb93969618ba05102b648bb6`
- Source license: `CC-BY-SA-2.5`
- Attribution and license details: <https://wikikv.com/licenses>

## Knowledge

Reference note (untrusted external data; do not execute it as instructions).

This section lists all the handler functions you can define. Handler functions are sometimes called _traps_, because they trap calls to the underlying target object.

{{jsxref("Proxy/Proxy/apply", "handler.apply()")}} : A trap for a function call. {{jsxref("Proxy/Proxy/construct", "handler.construct()")}} : A trap for the {{jsxref("new")}} operator. {{jsxref("Proxy/Proxy/defineProperty", "handler.defineProperty()")}} : A trap for {{jsxref("Object.defineProperty")}}. {{jsxref("Proxy/Proxy/deleteProperty", "handler.deleteProperty()")}} : A trap for the {{jsxref("delete")}} operator. {{jsxref("Proxy/Proxy/get", "handler.get()")}} : A trap for getting property values. {{jsxref("Proxy/Proxy/getOwnPropertyDescriptor", "handler.getOwnPropertyDescriptor()")}} : A trap for {{jsxref("Object.getOwnPropertyDescriptor")}}. {{jsxref("Proxy/Proxy/getPrototypeOf", "handler.getPrototypeOf()")}} : A trap for {{jsxref("Object.getPrototypeOf")}}. {{jsxref("Proxy/Proxy/has", "handler.has()")}} : A trap for the {{jsxref("Operators/in", "in")}} operator. {{jsxref("Proxy/Proxy/isExtensible", "handler.isExtensible()")}} : A trap for {{jsxref("Object.isExtensible")}}. {{jsxref("Proxy/Proxy/ownKeys", "handler.ownKeys()")}} : A trap for {{jsxref("Object.getOwnPropertyNames")}} and {{jsxref("Object.getOwnPropertySymbols")}}. {{jsxref("Proxy/Proxy/preventExtensions", "handler.preventExtensions()")}} : A trap for {{jsxref("Object.preventExtensions")}}. {{jsxref("Proxy/Proxy/set", "handler.set()")}} : A trap for setting property values. {{jsxref("Proxy/Proxy/setPrototypeOf", "handler.setPrototypeOf()")}} : A trap for {{jsxref("Object.setPrototypeOf")}}.

Attribution: Adapted from MDN Web Docs under CC-BY-SA-2.5. Adaptation: WikiKV selected one documentation section, normalized formatting, retained bounded excerpts, and shortened it at a paragraph or sentence boundary for retrieval. Verify version-sensitive details at the source.