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I am learning Java Script and I see the examples that were published a few years ago show __proto__ in the chrome developer tool - console while explaining the prototypical inheritance concept.

When I execute the same sample code I don't see __proto__ anymore in my current version of Chrome. I only see [[Prototype]].

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Questions:

  1. Hope both are the same? If yes, from which version that this change has taken place.
  2. Is it possible to revert my chrome developer tool to older version to view it as __proto__?
Bergi
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Athman
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    Yes, they are the same. `__proto__` was an implementation detail not originally mentioned in the ECMAScript specification, and was retroactively added to the standard to account for behavior that a lot of library code came to rely on. `[[Prototype]]` is how the specification has formally referred to that sub-object related to prototypical inheritance. – Patrick Roberts Mar 13 '23 at 04:27
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    It's the same thing, but the name `__proto__` was [deprecated](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/proto). – code Mar 13 '23 at 04:31

1 Answers1

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Yes, they are the same. It was reported as a bug and then changed somewhen around April 2021 (Chrome 92), to better align with the spec and follow Firefox devtools' lead.

No, you cannot change it back.

The [[prototype]] syntax reflects that it is an internal slot (also here) exposed only by the debugger, not some normal property. Using __proto__ as an alias causes quite some confusion, because object actually can have a normal property of that name, and there's also the old deprecated Object.prototype.__proto__ getter/setter that did access the [[prototype]].

Bergi
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