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import type { DeepReadonly } from './deep-readonly'
/**
* Recursively freezes an object and all of its properties. This prevents the
* object from being modified at runtime. When the JS runtime is running in
* strict mode, any attempts to modify a frozen object will throw an error.
*
* @see https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze
* @param obj The object to freeze.
*/
export function deepFreeze<T extends object>(obj: T): DeepReadonly<T> {
// If the object is already frozen, there's no need to freeze it again.
if (Object.isFrozen(obj)) return obj as DeepReadonly<T>
// An array is an object, but we also want to freeze each element in the array
// as well.
if (Array.isArray(obj)) {
for (const item of obj) {
if (!item || typeof item !== 'object') continue
deepFreeze(item)
}
return Object.freeze(obj) as DeepReadonly<T>
}
for (const value of Object.values(obj)) {
if (!value || typeof value !== 'object') continue
deepFreeze(value)
}
return Object.freeze(obj) as DeepReadonly<T>
}
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