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10 changes: 5 additions & 5 deletions 1-js/11-async/03-promise-chaining/01-then-vs-catch/solution.md
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The short answer is: **no, they are not equal**:

The difference is that if an error happens in `f1`, then it is handled by `.catch` here:

```js run
promise
.then(f1)
.catch(f2);
```

...But not here:

```js run
promise
.then(f1, f2);
```

That's because an error is passed down the chain, and in the second code piece there's no chain below `f1`.

In other words, `.then` passes results/errors to the next `.then/catch`. So in the first example, there's a `catch` below, and in the second one there isn't, so the error is unhandled.
6 changes: 3 additions & 3 deletions 1-js/11-async/03-promise-chaining/01-then-vs-catch/task.md
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# Promise: then versus catch

Are these code fragments equal? In other words, do they behave the same way in any circumstances, for any handler functions?

```js
promise.then(f1).catch(f2);
```

Versus:

```js
promise.then(f1, f2);
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