Is that (#2) defined behaviour, or is it undefined? Because iirc, other language... | Hacker News

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		Alphasite_ on June 25, 2014 \| parent \| context \| favorite \| on: V8 Optimization Killers Is that (#2) defined behaviour, or is it undefined? Because iirc, other languages disallow it for similar reasons.

gsnedders on June 25, 2014 [–]

Adding properties is undefined in ES5 and I believe defined in ES6.

Deleting properties is guaranteed to not break iteration and deleting an as-of-yet unvisited property causes it to never be visited.

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