es6 set 常见实用用法

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并集
//let setOfWords1 = new Set([1, 2, 3]);
//let setOfWords2 = new Set([3, 5, 2]);

var Array1 = [5,6,7,8,18,9,90,81]; 
var Array2 = [10,415,54,87,98,65,81];
let a = new Set(Array1);
let b = new Set(Array2); 
// 并集
let unionSet = new Set([...a, ...b]);
// set转化为数组
let unionSet1 = Array.from(unionSet);
console.log(unionSet1);
// 交集
let intersectionSet = new Set([...a].filter(x => b.has(x)));
// set转化为数组
let intersectionSet1 = Array.from(intersectionSet);
console.log(intersectionSet1);
// 差集
let differenceABSet = new Set(
.filter(x => !b.has(x)));
// set转化为数组
let differenceABSet1 = Array.from(differenceABSet);
console.log(differenceABSet1);

set 转为数组的另外一种方式
[...a] a 是一个set 对象