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Using Try/Catch with Async/Await
3:03Currently, we have no way to catch errors using async/await. In this video we'll learn how to use Node's try/catch block to catch and handle errors.
At present, to use async and
await with Express,
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we need some way to capture any errors
that might occur in our await function,
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like if something goes wrong with the
server when we try to create a new quote.
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Let's take a look at what
happens if an error occurs now.
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Above my code,
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I'll throw a fake error using
JavaScript's built-in error constructor.
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If we go back to Postman and
try to create a new quote again,
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you can see that our API isn't responding.
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It will just hang indefinitely and
that's not what we want.
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To address this, we need to wrap our
code in a JavaScript try-catch block.
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All the code we've written in this
route so far goes into the try block.
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The catch block takes one parameter,
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which represents whatever
error message it catches.
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Inside the catch block,
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we can send that message back to
the client in the form of JSON.
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For example, let's mimic if
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something went wrong by throwing this
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fake error inside of the try block.
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So what should happen is an error will be
thrown and this message will fall into
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the catch block and it will be
sent back to the client as JSON.
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So let's save, make sure the server
is running, and go back to Postman.
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We'll try to create the quote again, and
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now you see we're being
sent an error message.
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Notice, however, that we're still
getting back a status code of 200 OK,
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even though something
obviously went wrong.
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When something goes wrong, we wanna
make sure we're sending accurate HTTP
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status codes, as well as communicating
clear errors to the client.
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We'll talk about that in the next video.
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I'll go ahead and
erase the error we just made.
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And let's do this one more time by
refactoring our route handler that gets
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a single quote to use try-catch.
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I'll start by creating a try-catch block.
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Remembering to pass in the error.
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We'll copy and
paste our code into the try block.
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And now in the catch block,
in the event of an error,
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I can send back some JSON
containing an error message.
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For additional practice,
I recommend going back and
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refactoring this first route
to use try-catch as well.
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