let reverseWords = function (s) { ss = s.split(' '); for (let i = 0; i < ss.length; i++) { console.log(ss[i]); // ss[i] = reverseWord(ss[i]); l = 0; r = ss[i].length - 1; while (l <= r) { [s[i][l], s[i][r]] = [s[i][r], s[i][l]]; //上面这种方式无法成功交换两个值 //下面这种temp变量的方式也无法成功交换 let temp = ss[i][l]; ss[i][l] =ss[i][r]; ss[i][r] = temp; l++; r--; } } return ss.join(' ');};大神帮忙看一下上面的问题，二维数组交换值，交换不了。原因和原理是啥？