var coin = ['doge',
'binance',
'tron',
'litecoin',
'feyorra',
'ripple',
'ethereum',
'bitcoin'];
var urls = "https://bnbminers.site/earn/doge/"
function getLastPart(url) {
const parts = url.split('/');
let res;
if(parts.at(-1)=='') res = coin.indexOf(parts.at(-2));
else res = coin.indexOf(parts.at(-1));
urls = urls.replace(coin[res], coin[(res+1) % coin.length]);
return urls;
}
console.log(getLastPart(urls))