Web platform features explorer - __proto__

Web platform features explorer

This feature is discouraged — Changing __proto__ is slow and can cause surprising bugs.

For more information, see: https://tc39.es/ecma262/multipage/additional-ecmascript-features-for-web-browsers.html#sec-additional-ecmascript-features-for-web-browsers

The __proto__ property of objects partially exposes the prototype of an object.

Status

Discouraged

MDN documentation

Object.prototype.__proto__

Specifications

ECMAScript® 2026 Language Specification (#sec-object.prototype.__proto__), from TC39 (Ecma International).

Browser support

Chrome 1 Released on 2008-12-11
Chrome Android 18 Released on 2012-06-27
Edge 12 Released on 2015-07-29
Firefox 1 Released on 2004-11-09
Firefox for Android 4 Released on 2011-03-29
Safari 3 Released on 2007-10-26
Safari on iOS 1 Released on 2007-06-29

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