Adding React to a Vanilla Parcel Project

Create a Broadcaster in React with useState and useEffect Hooks

Create a Custom useBroadcaster Hook

Pass a Listener to a useCallback Hook

Create a Custom useListener Hook Around useCallback

Explaining the useListener Code

Map a Sequence of Values in React with useBroadcaster

Handling an Enter Keypress with useListener and React

Map a Sequence Based on Input Text in React

Creating a Debounce Operator to Limit Listener Calls

Wrap Fetch in a Broadcaster in React

Cancel a Fetch Request with a Broadcaster and React

Map an Error to a Broadcaster Value in React

Bringing the Pattern into React

Errors happen, so let's catch them and map them. This lesson walks through mapping an error to a different value to display to the user so they know what's happening when something goes wrong.

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https://app.egghead.io/api/v1/lessons/react-map-an-error-to-a-broadcaster-value-in-react/subtitles

Instructor: [0:00] Let's go ahead and handle this error in a graceful way. With promises, you do that with catch, so we can catch the error. For right now, just pass it down to the listener. I'll hit Save. Now, we caught the error and sent that down and it's logging the error out. With this error, I can write an operator to map it to something else.

[0:24] I'll write mapError as the name of our operator. Let us call our mapping function transform, and broadcaster, then listener. I can return the broadcaster, push the value through. If the value is an instance of error, then, I can, into the listener, transform that value. Otherwise, just do the default behavior.

[0:55] It's only going to do this if that value shows up as an error. Let's go ahead and use this around our broadcaster. We'll wrap this and say mapError. We'll take the error, and then just return something else. For now, I'll just say "Whoopsie," hit Save here. You can see, we get a Whoopsie out of here. I could do something like doing the error.message, hit Save, "The user aborted the request."

[1:24] If I wanted to target this login name right here, I could just map this to an object. That object is our profile, and it has a login on it of error.message. That would look like this, an object with a login. It has the message on it. If this didn't error, meaning we don't cancel, the object comes through fine. If it does error, then we can just map it to something else.

Map an Error to a Broadcaster Value in React

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Congrats on finishing Section 06: Bringing the Pattern into React!🎉🎉

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Bringing the Pattern into React