🔺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❗

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