Array.from()

Array.from()   伪数组转数组

1、 将对象转为数组

 

 

 

 2、将set结构转为数组

 let arr = [1,1,2,6,6,7,8,6];
 let set = new Set(arr);
 console.log(set); //{1,2,6,7,8}
 let arr1 = Array.from(set);
 console.log(arr1); //[1,2,6,7,8]

3、将map结构转为数组

 

 

 

 4、字符串转数组

var str = "123456";
var str1 = "say hello";
console.log(Array.from(str)); //['1', '2', '3', '4', '5', '6']
console.log(Array.from(str1)); //['s', 'a', 'y', ' ', 'h', 'e', 'l', 'l', 'o']

 5、实现数组拷贝

var oldArr = [1,2,3];
var newArr = Array.from(oldArr);
console.log(newArr); // [1,2,3]
console.log(oldArr == newArr); //false