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In this video.

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Let's see how we can handle what is called on handle rejection.

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An example of this kind of error is when the DB connection refused to connect to MongoDB, meaning if

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there are some connection error to MongoDB and then another type of error that it can be OC and the

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on handle rejection is that if we refuse to bring in catch block inside async await function and this

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kind of error is going to help us in the development mode.

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Let me show you an example inside the config file for the DB.

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Let's change the password and for this one if I check my terminal, you can see that we have some random

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string of error here.

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And again, if you are new to programming or especially to MongoDB, this kind of error message is,

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you know, be understand.

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So to be able to send the required or simplified message, we are going to handle this kind of can handle

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promise rejection.

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So how are we going to do it so we inside the server file, we need to create an instance of the server.

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So here we are going to assign a variable called server to what comes back from the app dot.

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Listen.

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And on this one we can change or listen to any event type.

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Remember, Node.js is an event driven technology, so it means that we can listen to types of events

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and the first type of event that we are going to listen to is what we call on handle rejection and we

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have access to that on the process dot on.

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And here we are listening to an event types and we have different types of events in Node.js.

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The one that we are going to handle is what we call on handle rejection, which is this one in our pass

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in a callback function.

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I have access to the actual error and then the promise.

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So here we go.

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So here I can go ahead and then console.log this simplified message.

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If you check the console, you can see that we have the message as back off, which is the authentication

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error, meaning that I pass a wrong password.

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So here we have access to those messages on error message and error dot name.

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So here you go back tick and then dollar sign replaces the error dot name.

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And then space dollar sign carry braces, error, dot message and that is it.

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So let's save it.

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And now let's check the console and you can see that we got simplify message as mongo server error but

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authentication meaning the authentication failed.

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All right.

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So here ends the section on how we can handle errors in experts charges.