refactor

1-js/11-async/05-promise-api/01-promise-errors-as-results/solution.md

@@ -0,0 +1,44 @@
+The solution is actually pretty simple.
+
+Take a look at this:
+
+```js
+Promise.all(
+  fetch('https://api.github.com/users/iliakan'),
+  fetch('https://api.github.com/users/remy'),
+  fetch('http://no-such-url')
+)
+```
+
+Here we have an array of `fetch(...)` promises that goes to `Promise.all`.
+
+We can't change the way `Promise.all` works: if it detects an error, then it rejects with it. So we need to prevent any error from occurring. Instead, if a `fetch` error happens, we need to treat it as a "normal" result.
+
+Here's how:
+
+```js
+Promise.all(
+  fetch('https://api.github.com/users/iliakan').catch(err => err),
+  fetch('https://api.github.com/users/remy').catch(err => err),
+  fetch('http://no-such-url').catch(err => err)
+)
+```
+
+In other words, the `.catch` takes an error for all of the promises and returns it normally. By the rules of how promises work, if a `.then/catch` handler returns a value (doesn't matter if it's an error object or something else), then the execution continues the "normal" flow.
+
+So the `.catch` returns the error as a "normal" result into the outer `Promise.all`.
+
+This code:
+```js
+Promise.all(
+  urls.map(url => fetch(url))
+)
+```
+
+Can be rewritten as:
+
+```js
+Promise.all(
+  urls.map(url => fetch(url).catch(err => err))
+)
+```