### **转化为数组** ``` var a = "abcacab"; var arr = a.split(""); arr.sort(); var temp = [arr[0]]; for (var i = 1; i < arr.length; i++) { if (arr[i] !== temp[temp.length - 1]) { temp.push(arr[i]); } } var b = temp.join("") console.log(b) ``` ### **ES6** ``` var a = "abcacab"; var c = [...new Set(a)].join("") console.log(c) ```