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This is not equivalent. It will result in y if x is any falsy value (like false, empty string, or 0), not just if x is nullish.

In which languages does ?: not work that way?

For example in PHP, it works exactly like you describe.

I think that’s exactly what the nullish ?? Operator is.

You can write x ?? y

Which is x !== null and x != undefined ? x : y

Kotlin.