// Immutable User in TypeScript
"use strict";
/*
This version ensures ALL exceptions activate at runtime.
- TypeScript is bypassed using (User as any)
- JavaScript strict mode is enabled
- Object.freeze() enforces runtime immutability
- deepFreeze() protects nested objects
*/
// Deep freeze for runtime immutability
function deepFreeze<T>(obj: T): T {
Object.freeze(obj);
for (const key of Object.keys(obj)) {
const value: any = (obj as any)[key];
if (typeof value === "object" && value !== null && !Object.isFrozen(value)) {
deepFreeze(value);
}
}
return obj;
}
// Immutable User type (compile-time)
type UserType = {
readonly id: number;
readonly name: string;
};
// Create immutable User object
const User: UserType = deepFreeze({
id: 42,
name: "Sophia"
} as const);
console.log("ID:", User.id);
console.log("Name:", User.name);
// Attempt 1: modify id
try {
(User as any).id = 100; // Cannot assign to read only property 'id'
} catch (e: any) {
console.log("Blocked:", e.message);
}
// Attempt 2: modify name
try {
(User as any).name = "Pet"; // Cannot assign to read only property 'name'
} catch (e: any) {
console.log("Blocked:", e.message);
}
// Attempt 3: add new property
try {
(User as any).age = 30; // Cannot add property age, object is not extensible
} catch (e: any) {
console.log("Blocked:", e.message);
}
// Attempt 4: delete property
try {
delete (User as any).name; // Cannot delete property 'name'
} catch (e: any) {
console.log("Blocked:", e.message);
}
/*
run:
ID: 42
Name: Sophia
Blocked: Cannot assign to read only property 'id' of object '#<Object>'
Blocked: Cannot assign to read only property 'name' of object '#<Object>'
Blocked: Cannot add property age, object is not extensi
*/
