JuniorTheoryCommon

What does tsc report for this file?

TypeScript

interface Order {
    readonly id: number;
    address: string;
}

const patch: Partial<Order> = {};
patch.address = "Oak 2";
patch.id = 8;

An error: the property id is read-only

Expecting Partial to remove readonly too: it only adds ?, so id stays read-only and the assignment is error TS2540.
Expecting const to freeze the object: it forbids only a new value for the variable, so patch.address = "Oak 2" compiles.

JuniorTheoryCommon

TypeScript

interface Order {
    readonly id: number;
    address: string;
}

const patch: Partial<Order> = {};
patch.address = "Oak 2";
patch.id = 8;

An error: the property id is read-only

Expecting Partial to remove readonly too: it only adds ?, so id stays read-only and the assignment is error TS2540.
Expecting const to freeze the object: it forbids only a new value for the variable, so patch.address = "Oak 2" compiles.