chuck
/
es6-11study


			
				
					
						
						
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							<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>rest</title>
</head>
<body>
    <script>
        /**
         * 值唯一
         * 不能运算
         * 不能使用for in，可以使用reflect.ownkeys
         */

         //创建symbol
         let s = Symbol()
         console.log(s,typeof s)  //Symbol() "symbol"

         let s1 = Symbol('chuck')  //描述字符串
         let s2 = Symbol('chuck')  //描述字符串
         console.log(s1)   //Symbol(chuck)
         console.log(s1 === s2)  //false

         let s3 = Symbol.for('chuck')  //函数对象
         let s4 = Symbol.for('chuck')
         console.log(s3,typeof s3)  //Symbol(chuck) "symbol"
         console.log(s3 === s4) // true

         //不能运算 否则报错
         //let result = s + 100;

         //数据类型
         //USONB   you are so niubility
         /**
          * undefined
          * string
          * object
          * null 
          * symbol
          */
        
        //symbol 使用场景
        //给对象添加方法 up down -- 可以很安全的加入方法
        let game = { }
        let methods = {
            up: Symbol(),
            down: Symbol()
        }
        game[methods.up] = function(){}
        game[methods.down] = function(){}

        //2
        let cc = {
            name : 'chuck',
            [Symbol('say')]:function(){}
        }

        // symbol 内置属性 共11个
        /**
         * hasInstance
         * match
         * replace
         * isConcatSpreadable 
         */
        class Person{
            //自动执行
            static [Symbol.hasInstance](param){
                console.log(param)  //{d:2}
                console.log('检测')
            }
        }
        let o = {d:2}
        console.log(o instanceof Person)

        const arr = [1,2,3]
        const arr1 = [4,5,6]
        arr1[Symbol.isConcatSpreadable] = false;//不可展开 合并
        console.log(arr.concat(arr1))
    </script>
</body>
</html>