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30-seconds-of-code/snippets/deepFreeze.md
2018-09-01 12:01:02 +02:00

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### deepFreeze
Deep freezes an object.
Calls `Object.freeze(obj)` recursively on all unfrozen properties of passed object that are `instanceof` object.
```js
const deepFreeze = obj =>
Object.keys(obj).forEach(
prop =>
!obj[prop] instanceof Object || Object.isFrozen(obj[prop])
? null
: deepFreeze(obj[prop])
) || Object.freeze(obj);
```
```js
'use strict';
const o = deepFreeze([1, [2, 3]]);
o[0] = 3; // not allowed
o[1][0] = 4; // not allowed as well
```