up

1-js/11-async/07-async-await/02-rewrite-async-2/solution.md

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+
+There are no tricks here. Just replace `.catch` with `try...catch` inside `demoGithubUser` and add `async/await` where needed:
+
+```js run
+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();
+```

1-js/11-async/07-async-await/02-rewrite-async-2/task.md

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+
+# Rewrite "rethrow" async/await
+
+Below you can find the "rethrow" example from the chapter <info:promise-chaining>. Rewrite it using `async/await` instead of `.then/catch`.
+
+And get rid of the recursion in favour of a loop in `demoGithubUser`: with `async/await` that becomes easy to do.
+
+```js run
+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();
+```