• masterspace@lemmy.ca
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    10 hours ago

    Because that object is of a type where that member may or may not exist. That is literally the exact same behaviour as Java or C#.

    If I cast or type check it to make sure it’s of type Bar rather than checking for the member explicitly it still works:

    And when I cast it to Foo it throws a compile time error, not a runtime error:

    I think your issues may just like in the semantics of how Type checking works in JavaScript / Typescript.