Set对象的存储类型为唯一值，这个值与数据类型无关。
set在出现重复值时，自动将重复的值删除。
<script>
let mySet=new Set();
mySet.add(1);
mySet.add("test");
mySet.add(3);
mySet.add(3);
mySet.add("3");
mySet.delete("3");
mySet.forEach(function(value){
console.log(value);
});
</script>
类型转换
Set与Array的相互转化：
<script>
let myArray=["value1","value2","value3"];
console.log("-----Array to Set----");
let mySet=new Set(myArray);
console.log(mySet);
console.log("-----Set to Array----")
let myArray1=[...mySet];
console.log(myArray1);
</script>
string 转 Set (Set不可以通过toString转化为string),
<script>
let mySet=new Set("Happy");
console.log(mySet);//{"H", "a", "p", "y"}
</script>Set对象作用
1.数组去重
2.并集
3.交集
4.差集
<script>
let myArray=[1,2,2,3,3,4]
let mySet=new Set(myArray);
myArray=[...mySet];
console.log("---数组去重---");
console.log(myArray);//(4) [1, 2, 3, 4]
let s1=new Set([1,2,3]);
let s2=new Set([2,3,4,5]);
console.log("---并集---");
let unionSet=new Set([...s1,...s2]);
console.log(unionSet);
console.log("---交集---");
let intersect=new Set([...s1].filter(x=>s2.has(x)));
console.log(intersect);//Set(2) {2, 3}
console.log("---差集---");
let difference=new Set([...s1].filter(x=>!s2.has(x)));
console.log(difference);//Set(1) {1}
</script>