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Update deepFreeze.md

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Angelos Chalaris
2020-03-17 16:02:41 +02:00
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parent 11b046af0a
commit bc1233c283
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snippets/deepFreeze.md
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@ -5,13 +5,17 @@ tags: object,recursion,intermediate
Deep freezes an object. Deep freezes an object.
Calls `Object.freeze(obj)` recursively on all unfrozen properties of passed object that are `instanceof` object. Use `Object.keys()` to get all the properties of the passed object, `Array.prototype.forEach()` to iterate over them.
Call `Object.freeze(obj)` recursively on all properties, checking if each one is frozen using `Object.isFrozen()` and applying `deepFreeze()` as necessary.
Finally, use `Object.freeze()` to freeze the given object.
```js ```js
const deepFreeze = obj => const deepFreeze = obj => {
Object.keys(obj).forEach(prop => Object.keys(obj).forEach(prop =>
!(obj[prop] instanceof Object) || Object.isFrozen(obj[prop]) ? null : deepFreeze(obj[prop]) obj[prop] = typeof obj[prop] === 'object' && !Object.isFrozen(obj[prop]) ? deepFreeze(obj[prop]) : obj[prop]
) || Object.freeze(obj); );
return Object.freeze(obj);
}
``` ```
```js ```js
@ -21,4 +25,4 @@ const o = deepFreeze([1, [2, 3]]);
o[0] = 3; // not allowed o[0] = 3; // not allowed
o[1][0] = 4; // not allowed as well o[1][0] = 4; // not allowed as well
``` ```