JSFiddle - React, Tailwind, and code Playground

JavaScript

var arr= [  "apple","cat","truck","APPLE","CAT","TRUCK"];

 arr.sort(sort);
function sort(a, b){
    
   if(a.toLowerCase() > b.toLowerCase()) return 1;
       if(a.toLowerCase() < b.toLowerCase()) return -1;
    return 0;
}
document.write(arr);