What does symbol mean in js

A Symbol in JavaScript is a unique primitive value used to create private properties, namespaces, and mapped objects. Symbols ensure uniqueness, prevent reuse or duplication, and description information can be accessed through the Symbol.description property. However, Symbol is not supported in legacy environments, unlike other primitive value types, and is not serializable.

Symbol: The magic value in JavaScript

In JavaScript, Symbol is a special primitive value type , represents a unique and immutable identifier. It differs from other primitive value types (such as strings, numbers, and booleans) in that it cannot be reused or copied.

Uses of Symbol

Symbol is mainly used in the following aspects:

• Create private attributes: Symbol Can be used as a key to an object's properties, making them private, preventing accidental overwriting or modification.
• Namespace: Symbol can be used to create a global namespace to avoid variable conflicts, especially in modular code.
• Mapped objects: Symbols can be used as keys for objects to provide a more efficient and concise way to store and retrieve values.

Create Symbol

You can use the following syntax to create a Symbol:

<code>const mySymbol = Symbol();</code>

Use Symbol

To use Symbol, you can use it as a property key or value. For example:

<code>const myObject = {};
myObject[mySymbol] = '秘密数据';</code>

Uniqueness of Symbol

One of the key properties of Symbol is its uniqueness. Each Symbol created using the Symbol() method is guaranteed to be unique, meaning they cannot be reused or copied by other code.

Description of Symbol

Although a Symbol is immutable, it can have a description string that is used to provide information in debugging or error messages. This description can be accessed using the Symbol.description property.

For example:

<code>const mySymbol = Symbol('私有数据');
mySymbol.description; // '私有数据'</code>

Notes on Symbol

• Symbol was only introduced in ES6, so it does not work in older JavaScript environments Supported.
• Symbol is different from other primitive value types and therefore cannot be compared or cast with them.
• Symbol cannot be serialized and therefore cannot be transmitted in JSON or local storage.

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