JSFiddle - React, Tailwind, and code Playground

JavaScript

var string='ACBacb';
alert(string.split('').sort(caseInsensitiveSort).join(''));

function caseInsensitiveSort(a, b) 
{ 
   var ret = 0;
   a = a.toLowerCase();b = b.toLowerCase();
   if(a > b) 
      ret = 1;
   if(a < b) 
      ret = -1; 
   return ret;
}