function SwapPairs(str) {
if (str == null || (str.length === 0)) {
return str;
}
let arr = str.split('');
for (let i = 0; i < arr.length - 1; i += 2) {
let tmp = arr[i];
arr[i] = arr[i + 1];
arr[i + 1] = tmp;
}
return arr.join("");
}
const str = "aBcDeFgHiJkLmN";
console.log(SwapPairs(str));
/*
run:
BaDcFeHgJiLkNm
*/