61 lines
1.7 KiB
Markdown
61 lines
1.7 KiB
Markdown
---
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title: Object Freeze
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---
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## Object Freeze
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The `Object.freeze()` method freezes an object. A frozen object will *prevent you* from:
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* Adding new properties to it
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* Removing existing proprerties from it
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* Changing the enumerability, configurability, or writeability of it's existing properties
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### Syntax
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```javascript
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Object.freeze(obj)
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```
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### Parameters
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`obj`
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* The object to freeze.
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### Returns
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The frozen object.
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### Important Note
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Attempting to add, remove, or modify properties of a frozen object will result in a failure. This failure will either be silent or a thrown `TypeError` (if Strict Mode is enabled). Additionally, `Object.freeze()` is a shallow operation. This means that nested object, of a frozen object, are modifiable.
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### Example
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```javascript
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// Create your object
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let person = {
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name: 'Johnny',
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age: 23,
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guild: 'Army of Darkness',
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hobbies: ['music', 'gaming', 'rock climbing']
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}
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// Modify your object
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person.name = 'John'
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person.age = 24
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person.hobbies.splice(1,1)
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delete person.guild
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// Verify your object has been modified
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console.log(person) // { name: 'John', age: 24, hobbies: ['music', 'rock climbing']
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// Freeze your object
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Object.freeze(person)
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// Verify that your object can no longer be modified
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person.name = 'Johnny' // fails silently
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person.age = 23 // fails silently
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console.log(person) // { name: 'John', age: 24, hobbies: ['music', 'rock climbing']
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// The freeze is "shallow" and nested objects (including arrays) can still be modified
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person.hobbies.push('basketball')
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consol.log(person.hobbies) // ['music', 'rock climbing', 'basketball']
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```
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#### More Information:
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[MDN Documentation](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/freeze)
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