数组去重
let arr1 = [10,20,33,10,20,33,1,2,3]
let s = new Set(arr1) // 去重
console.log(s) // Set(6) {10, 20, 33, 1, 2, …}
let arr2 = [...s]
// [10, 20, 33, 10, 20, 33, 1, 2, 3] (6) [10, 20, 33, 1, 2, 3]
console.log(arr1,arr2)
字符串的去重
var str = 'hello'
var s2 = new Set(str)
var newStr = [...s2].join('');
console.log(newStr)
