33 lines
765 B
Markdown
33 lines
765 B
Markdown
---
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title: Deep freeze object
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type: snippet
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language: javascript
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tags: [object,recursion]
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cover: camper-school-bus
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dateModified: 2020-10-19T18:51:03+03:00
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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()` recursively on all properties, 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(prop => {
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if (typeof obj[prop] === 'object') deepFreeze(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 val = deepFreeze([1, [2, 3]]);
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val[0] = 3; // not allowed
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val[1][0] = 4; // not allowed as well
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```
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