JavaScript问题

var arr=['red','blue','pink','green'];
var str =' ';
for () {

//第一种
var arr=['red','blue','pink','green'];
var str =Array.from(arr.join('')).sort().join("&");
console.log(str);

//第二种
var arr=['red','blue','pink','green'];
var str ='';
arr.forEach(e=>{
   str+=e;
});
str = Array.from(str).sort().join("&")
console.log(str);