@litert/utils

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Function deepFreeze ​

Source: DeepFreeze.ts

Recursively applies Object.freeze() to an object and all of its nested object and array properties, making the entire structure immutable. The return type reflects the deep-readonly transformation as IDeepReadonly<T>.

WARNING

This function does not clone the object. It freezes the original object and all its nested properties in-place.

Import ​

ts
import { deepFreeze } from '@litert/utils-object';

Signature ​

ts
function deepFreeze<T extends IObject>(obj: T): IDeepReadonly<T>;

Parameters ​

  • Parameter obj: T

    The object to be deeply frozen. This object and all its nested object and array properties are frozen directly — no clone is made.

Return Value ​

IDeepReadonly<T> — the same object reference as the input, now fully frozen and typed as deeply readonly. All nested objects and arrays are also frozen.

Examples ​

ts
import { deepFreeze } from '@litert/utils-object';

const obj = deepFreeze({ a: 1, b: [{ c: 2 }, 123] });
obj.a = 10;       // Throws TypeError in strict mode
obj.b[0].c = 99;  // Throws TypeError in strict mode

Circular references ​

deepFreeze tracks already-processed objects internally, so circular references are handled safely without causing infinite loops.

ts
import { deepFreeze } from '@litert/utils-object';

const a: any = { x: 1 };
a.self = a; // circular reference

deepFreeze(a); // safe — does not recurse infinitely