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create an instance from class extends null is allowed but it should not #25187

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Kingwl opened this issue Jun 25, 2018 · 3 comments

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Working as Intended

Contributor

Kingwl commented Jun 25, 2018

TypeScript Version: 3.0.0-dev.201xxxxx

Search Terms:

Code

class A extends null { }

new A()

Expected behavior:

Uncaught TypeError: Super constructor null of A is not a constructor

Actual behavior:

everything is ok

Playground Link:

https://www.typescriptlang.org/play/index.html#src=class%20A%20extends%20null%20%7B%20%7D

Related Issues:

ghost added the Suggestion label

Contributor

mhegazy commented Jun 25, 2018

This looks like a bug in the runtime. An ES2015 class can extend null.

See spec definiton of evaluating null heritage clauses: https://www.ecma-international.org/ecma-262/6.0/#sec-runtime-semantics-classdefinitionevaluation
And MDN docs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/extends#Extending_null

mhegazy added Working as Intended and removed Suggestion labels

Contributor Author

Kingwl commented Jun 26, 2018

tc39/ecma262#1036

Collaborator

typescript-bot commented Jul 11, 2018

Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.

typescript-bot closed this as completed

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