Detailed explanation of Symbol class in JS

The Symbol data type in JavaScript is a basic data type used to represent unique values. Characteristics of Symbol: 1. Unique, each Symbol value is unique and will not be equal to any other value; 2. Immutability, once the Symbol value is created, it cannot be modified or reassigned; 3. Hiddenness, the Symbol value cannot be modified or reassigned; It will be implicitly converted to other types; 4. It cannot be enumerated. When the Symbol value is used as the attribute name of the object, it is not enumerable by default.