33 lines
805 B
Markdown
33 lines
805 B
Markdown
---
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title: deepFreeze
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tags: object,recursion,intermediate
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---
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Deep freezes an object.
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Use `Object.keys()` to get all the properties of the passed object, `Array.prototype.forEach()` to iterate over them.
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Call `Object.freeze(obj)` recursively on all properties, checking if each one is frozen using `Object.isFrozen()` and applying `deepFreeze()` as necessary.
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Finally, use `Object.freeze()` to freeze the given object.
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```js
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const deepFreeze = obj => {
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Object.keys(obj).forEach(
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prop =>
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(obj[prop] =
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typeof obj[prop] === 'object' && !Object.isFrozen(obj[prop])
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? deepFreeze(obj[prop])
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: obj[prop])
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);
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return Object.freeze(obj);
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};
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```
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```js
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'use strict';
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const o = deepFreeze([1, [2, 3]]);
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o[0] = 3; // not allowed
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o[1][0] = 4; // not allowed as well
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```
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