44 lines
1.2 KiB
Markdown
44 lines
1.2 KiB
Markdown
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))
|
|
)
|
|
```
|