编辑代码

let s1 = Symbol("foo")
let s2 = Symbol("bar")
console.log(s1,s2)
const obj = {
    toString(){
        return 'abc'
    }
}
const sym = Symbol(obj)
console.log(sym)
console.log(String(sym),sym.toString())
let s3 = Symbol()
console.log(Boolean(!s3))
//Symbol可以转为布尔值，显示的转为字符串