🔺Symbol

JS ⟩ value ⟩ primitive ⟩ symbol

returns a primitive value that's guaranteed to be unique.

const unique = Symbol()    // ⭐️ not `new Symbol()`❗️ 
let obj = {
    [unique]: <value>,     // symbol used as a computed property name
};

⭐️ 重點

Symbols

• only used as (computed) property names.❗

• are primitive values, not objects, Symbol() is not a constructor.❗

• can't invoke with new❗

🔴 主題

• Symbol.iterator - name of a required method for iterables.

👥 相關

• Symbols can be used as computed property names.

• object literal

📗 參考

• JavaScript: The Definitive Guide ⟩

  • 3.6 Symbols

  • 6.10.3 Symbols as Property Names

📘 手冊

• Symbol