أعد كتابة "rethrow" مع غير متزامن / انتظار

Below you can find the “rethrow” example. Rewrite it using async/await instead of .then/catch.

وتخلص من العودية لصالح حلقة في demoGithubUser: مع` غير متزامن / انتظار 'يصبح من السهل القيام به.

class HttpError extends Error {
  constructor(response) {
    super(`${response.status} for ${response.url}`);
    this.name = 'HttpError';
    this.response = response;
  }
}

function loadJson(url) {
  return fetch(url).then((response) => {
    if (response.status == 200) {
      return response.json();
    } else {
      throw new HttpError(response);
    }
  });
}

// Ask for a user name until github returns a valid user
function demoGithubUser() {
  let name = prompt('Enter a name?', 'iliakan');

  return loadJson(`https://api.github.com/users/${name}`)
    .then((user) => {
      alert(`Full name: ${user.name}.`);
      return user;
    })
    .catch((err) => {
      if (err instanceof HttpError && err.response.status == 404) {
        alert('No such user, please reenter.');
        return demoGithubUser();
      } else {
        throw err;
      }
    });
}

demoGithubUser();

There are no tricks here. Just replace .catch with try..catch inside demoGithubUser and add async/await where needed:

class HttpError extends Error {
  constructor(response) {
    super(`${response.status} for ${response.url}`);
    this.name = 'HttpError';
    this.response = response;
  }
}

async function loadJson(url) {
  let response = await fetch(url);
  if (response.status == 200) {
    return response.json();
  } else {
    throw new HttpError(response);
  }
}

// Ask for a user name until github returns a valid user
async function demoGithubUser() {
  let user;
  while (true) {
    let name = prompt('Enter a name?', 'iliakan');

    try {
      user = await loadJson(`https://api.github.com/users/${name}`);
      break; // no error, exit loop
    } catch (err) {
      if (err instanceof HttpError && err.response.status == 404) {
        // loop continues after the alert
        alert('No such user, please reenter.');
      } else {
        // unknown error, rethrow
        throw err;
      }
    }
  }

  alert(`Full name: ${user.name}.`);
  return user;
}

demoGithubUser();