JS Title: input array, exchange the largest with the first element, exchange the smallest with the last element, and output array.

var arr34 = [1, 4, 32, 4, 5, 7, 8];// Actual output  [32,4,8,4,5,7,1]
var arr_new_34 = [].concat(arr34);// Deep copy 
arr_new_34.sort(function (a, b) {
     return a > b ? 1 : -1; });// Sort to find the maximum and minimum value 
var max = arr_new_34[arr_new_34.length - 1];
var min = arr_new_34[0];
var maxIndex = arr34.indexOf(max);// Get the maximum value in the subscript of the original array 
[arr34[0], arr34[maxIndex]] = [arr34[maxIndex], arr34[0]];// Swap the maximum value with the first element  --  Deconstruct assignment 
//***  Be careful   If the first time you exchange positions is to exchange the maximum and minimum positions   here   The subscript of the minimum value has changed   Turned into  2  Turned out to be  0 
// So the subscript of the minimum value has to wait until the position is obtained after the exchange 
var minIndex = arr34.indexOf(min);// Get the minimum value in the subscript of the original array 
[arr34[arr34.length - 1], arr34[minIndex]] = [arr34[minIndex], arr34[arr34.length - 1]];// Swap the minimum value with the first element 
console.log(arr34.join(","));