add last 3 to front and back
JavaScript
function newStr(str){
if (str.length<3){
return str+"</br>";
}
var mdStr = str.substring((str.length - 3) , (str.length));
return(mdStr + str + mdStr+"</br>");
}
document.write(newStr("a"));
document.write(newStr("abc"));
document.write(newStr("abcd"));