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

You often want to ignore values until the user performs a certain action. This lesson walks through setting up an `allowWhen` broadcaster that will only pass the latest value through when another broadcaster fires. The scenario is using an `Enter` keypress to allow the latest value of the input text to be passed through.

Instructor: [0:00] Since we have a text box, let's put it to good use by allowing ourselves to type something into the text box. Hit Enter and show all those words in sequence. My first thought is that, we need to wait to detect. When we hit enter, we're going to do this onkeypress and set up an onkeypress listener up here.

[0:20] We'll say, "Let onkeypress, and this is a useListener." If the idea is to get the text off of onInput, that means we can bring in target values. We'll do that here, target value. I'll call this input value and wrap target value around onInput.

[0:43] Onkeypress, I only want that to broadcast when the enter key comes through. We'll bring in filter and save that enter is filtered by an event where the event.key is equal to enter, and then wrap that around onkeypress.

[1:06] The way these two work together can look something like an allow when operator, where I can have an allow broadcaster, then the main broadcaster listener, then we can track the current value from our broadcaster where we just say that current is equal to the value.

[1:28] Our allow broadcaster would just ignore any values, but instead send the current down to the listener. You think of this as the input event getting the text from the text field, and then this as the Enter key, which will take the current text and then just pass that along.

[1:49] We can use this together inside of here where I can take the input value, and then wrap that with an allow when you hit Enter. Hit Save there, and now type something. Hit the Enter key, and then the text shows below. Type another thing. Hit Enter, and the net text changes.

Course

Bringing the Pattern into React

Handling an Enter Keypress with useListener and React

Share this video with your friends