Symbol common methods and characteristics

Reference to reprint Symbol address:
https://es6.ruanyifeng.com/#docs/symbol
ES6 introduces a new primitive basic data Symbol, which is the seventh data type of the JavaScript language. The first six are: undefined, null , Boolean, String, Number, Object.
Today I sorted out some of the more commonly used features and methods of Symbol.

Symbol awareness

1. Uniqueness

 const s = Symbol(); //创建一个Smbol类型的数据
 console.log(s)
 const x = Symbol();

2. Each Symbol value has a tag string, which is obtained through the Symbol.description property

  // 给Symbol类型的数据分配一个字符串
        const c = Symbol('foo');
        const d = Symbol('rdd');
        console.log(c.description)
        console.log(d.description)

3. When Symbol is used as a property name, you must add [].
   Object properties (instance properties) generally have only two types: string.
   
   
   If Symbol is assigned like this , if you want to get 90, you can deconstruct it:

  obj[Symbol()] = 90

4. Symbol.for()

   It will be registered with a marked string.
   Not only is it a Symbol value, but also a one-
   to-one correspondence between the string in for and the Symbol. Accepts a string and returns a Symbol value. At the same time, it will register a global correspondence between the string and the Symbol value.
   If the string has already been registered, return its corresponding Symbol value

 // 注册Symbol与字符串的关系
        const e = Symbol.for('e')
        const f = Symbol.for('e')
        console.log(e === f)//true

5. Symbol.keyFor():
   Returns the registered key, accepts a Symbol value, and returns its corresponding string for the Symbol value generated by fro
   
6. According to the attribute name, the
   attribute name is a string type, and the
   attribute name is a symbol type.
   By obj.getOwnPropertySymbol obtaining its own attribute Symbol value, obtaining the attribute of the instance itself with the Symbol type as the key

  object.getOwnPropertySymbol(obj)