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>Document</title>
</head>
<body>
    <script>
        //二维数组
        const result = Object.fromEntries([
            ['name','hi'],
            ['age','15,34,45']
        ])
        console.log(result)  //{name:'hi',age:'15,34,45'}

        //Map
        const m = new Map()
        m.set('name','zhang')
        const result1 = Object.fromEntries(m)
        console.log(m)

        //es8中 Object.entries  对象转数组
        const arr = Object.entries({
            name:'zhang'
        })
        console.log(arr)

        //2、trimStart
        let str = '   hi   '
        console.log(str)
        console.log(str.trimStart())
        console.log(str.trimEnd())
        console.log(str.trim())

        //3、flat、flatMap  数组的两个方法 平 将多维数组转低维数组
        const arr1 = [1,2,3,[4,5]]
        console.log(arr1.flat())
        const arr2 = [1,2,3,[4,5,[6,7]]]
        console.log(arr2.flat(2))  //2表示深度

        const arr3 = [1,2,3,4]
        const result2 = arr3.flatMap(item=>[item*10])
        console.log(result2)

        //4、Symbol.prototype.description
        let s = Symbol('beida')
        console.log(s.description)  //beida
    </script>
</body>
</html>