do...while

let result = "";
let i = 0;

do {
  i += 1;
  result += i;
} while (i < 5);

console.log(result);
// : "12345"

do
  statement
while (condition);

let result = "";
let i = 0;
do {
  i += 1;
  result += `${i} `;
} while (i > 0 && i < 5);
// i === 0 

console.log(result);

do {
  if (!user.loggedIn) {
    console.log("");
    break;
  }
  const friends = user.getFriends();
  if (!friends.length) {
    console.log("");
    break;
  }
  for (const friend of friends) {
    handleFriend(friend);
  }
} while (false);
// The rest of code

handleFriends: {
  if (!user.loggedIn) {
    console.log("");
    break handleFriends;
  }
  const friends = user.getFriends();
  if (!friends.length) {
    console.log("");
    break handleFriends;
  }
  for (const friend of friends) {
    handleFriend(friend);
  }
}

function handleFriends() {
  if (!user.loggedIn) {
    console.log("");
    return;
  }
  const friends = user.getFriends();
  if (!friends.length) {
    console.log("");
    return;
  }
  for (const friend of friends) {
    handleFriend(friend);
  }
}

do {
  // 
} while ((match = regexp.exec(str)));