Cannot delete from inferred types without typing them first

[gabriel-peracio]

Bug Report

🔎 Search Terms

Cannot delete from inferred types without typing them first

🕗 Version & Regression Information

• This changed between versions 3.9 and 4.0

⏯ Playground Link

Playground link with relevant code

💻 Code

const someObject = {
    foo: 'bar',
    baz: true
}

delete someObject.foo // The operand of a 'delete' operator must be optional.(2790)

🙁 Actual behavior

You cannot delete from a literal object without facing the error.
You are forced to type the object, marking the property you want to delete as optional, even though it is not optional up until that point.

🙂 Expected behavior

Since you never provided a type to the object, you should be able to delete from it, and afterwards it gets marked as optional.
Alternatively, the check should be divorced from strictNullChecks so it can be turned off separately

[fatcerberus]

This is intentional. You also can’t assign new properties after the fact either.

[RyanCavanaugh]

This behavior was specifically requested; see #13783.

[fatcerberus]

@RyanCavanaugh fwiw 13783 involves explicit type annotations - the OP here has an inferred object literal and seems to be expecting it to act as an evolving type.

Maybe worth noting that there’s no way to declare a property as optional in an object literal without a type annotation…

[typescript-bot]

This issue has been marked 'Working as Intended' and has seen no recent activity. It has been automatically closed for house-keeping purposes.