const arr = ["javascript", "c", "c++", "c#", "python", "php"];
const last = arr[arr.length - 1];
console.log(last);
const first = arr[0];
console.log(first);
console.log(arr[1]);
console.log(arr.at(-1));
console.log(arr[-1]); // undefined
console.log(arr[2]);
console.log(arr.at(-2));
/*
run:
"php"
"javascript"
"c"
"php"
undefined
"c++"
"python"
*/