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52 changes: 42 additions & 10 deletions src/App.jsx
Original file line number Diff line number Diff line change
@@ -1,16 +1,48 @@
import './App.css';
import Data from './data/messages.json';

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Prefer to use a lower camelcase symbol here. The import name becomes the variable name used in this file to refer to the data, which here is a list of data, not a class (yes React uses capital letters even though they're functions, but conceptually, they're like a class). An ALL_CAPS name would also be OK.

import ChatLog from './components/ChatLog';
import { useState } from 'react';


function App () {
const [messageData, setMessageData] = useState(Data);

const senders = [...new Set(Data.map(message => message.sender))];

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Nice use of map to extract the sender information, then uniquing that with a Set to get the participants in the conversation. We can confirm with the docs that iterating over the Set contents will occur in insertion order, meaning the resulting list of senders, however many there are, will be in the order they participated in the conversation.


const handleLiked = (id) => {

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👍 Since our state is defined here, we also need to define our mutating function here so that it can "see" the setter function. All we need to receive is the id of the message to toggle, which allows us to locate the message to update, and calculate the next state value. We can pass this all the way down to our ChatEntry which handles the click event, passing us the id of the message that was clicked.

setMessageData(messageData => messageData.map(message => {

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Nice use of the callback setter style. In this application, it doesn't really matter whether we use the callback style or the value style, but it's good practice to get in the habit of using the callback style.

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Nice use of map here to both handle making a new list so that React sees the message data has changed, and make new data for the clicked message with its like status toggled.

if (message.id === id) {
return {...message, liked: !message.liked};

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We showed this approach in class, but technically, we're mixing a few responsibilities here. rather than this function needing to know how to change the liked status itself, we could move this update logic to a helper function. This would better mirror how we eventually update records when there's an API call involved.

In this project, our messages are very simple objects, but if we had more involved operations, it could be worthwhile to create an actual class with methods to work with them, or at least have a set of dedicated helper functions to centralize any such mutation logic.

} else {
return message;
};
}));
};

const calcTotalLiked = (messageData) => {
let total = 0;
for (const message of messageData) {
if (message.liked) {
total += 1;
}
};
return total;
};

const totalLiked = calcTotalLiked(messageData);
Comment on lines +22 to +32

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Nice job determining the total likes based on the like data of each message. We don't need an additional piece of state to track this, since it can be derived from the existing state we are tracking.

Explicitly totalling the count is perfectly fine, but many JS programmers would use reduce to achieve this.

  const calcTotalLiked = (messageData) => {
    return messageData.reduce((acc, message) => {
      return message.liked ? acc + 1 : acc;
    }, 0);
  };

The first few times we work with reduce, it can be challenging to understand, but it's a tool that gets used commonly enough that it's worth practicing.


const App = () => {
return (
<div id="App">
<header>
<h1>Application title</h1>
</header>
<main>
{/* Wave 01: Render one ChatEntry component
Wave 02: Render ChatLog component */}
</main>
</div>
<>
<div id="App">
<header>
<h1>Chat between {senders[0]} and {senders[1]}</h1>

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For the conversation in the project, there are exactly two participants and both have sent messages, which is the only reason we can find them. What would happen for other conversation situations?

  • no one has sent a message yet
  • only one participant has sent a message (the local user? a remote user?)
  • there are more than two participants in this conversation

Some of these cases might not really be workable given the limited data we're working with, but it's worth thinking about what this could look like for a more complete application.

<h2>{totalLiked} ❤️s</h2>
</header>
<main>
<ChatLog entries = {messageData} onLiked={handleLiked}/>
</main>
</div>
</>
);
};

Expand Down
43 changes: 33 additions & 10 deletions src/components/ChatEntry.jsx
Original file line number Diff line number Diff line change
@@ -1,20 +1,43 @@
import './ChatEntry.css';
import PropTypes from 'prop-types';
import TimeStamp from './TimeStamp';

const ChatEntry = ({sender, body, timeStamp, id, liked, onLiked}) => {

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👍 I like using destructured props to make it more visibly clear in the function definition itself what props we're expecting to receive. We do need to remember that these are all passed in as a single object (the one we usually call props) and it can cause problems if we forget to include the destructuring syntax (it's easy to forget and list the props as multiple separate params) I really prefer the glanceability.

const heart = liked ? '❤️' :'🤍' ;

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👍 We can figure out which emoji to use for the liked status based on the liked prop without creating any additional state.


const localOrRemote = sender === 'Vladimir' ? 'chat-entry local' : 'chat-entry remote';

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Nice logic to decide whether to treat a message as local or remote. How could we generalize this so that it didn't need to look explicitly for Vladimir? This project only passes in a single conversation, but ideally, our components should work in other situations.

In the general case, does the ChatEntry itself have enough information as it is to "know" which messages are local and which are remote?


const onLikeClicked = () => {
onLiked(id);

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👍 Passing the id of this message lets the logic defined up in the App find the message to update in its data.

};

const ChatEntry = () => {
return (
<div className="chat-entry local">
<h2 className="entry-name">Replace with name of sender</h2>
<section className="entry-bubble">
<p>Replace with body of ChatEntry</p>
<p className="entry-time">Replace with TimeStamp component</p>
<button className="like">🤍</button>
</section>
</div>
<>
<div className={localOrRemote}>
<h2 className="entry-name">{sender}</h2>
<section className="entry-bubble">
<p>{body}</p>
<p className="entry-time">
<TimeStamp time = {timeStamp} />

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Nice use of the supplied TimeStamp. All we need to do is pass in the timeStamp string from the message data and it takes care of the rest. All we had to do was confirm the name and type of the prop it was expecting (which we could do through its PropTypes) and we're all set!

Nit: no spaces around attribute =

</p>
<button
className="like"
onClick={onLikeClicked}>

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👍 We need a wrapper of some kind rather than calling the received callback through props, since our callback function is expecting a message id as its parameter. If we tried to use it directly as the click event handler, React would end up passing it a clink event, since any function registered as an event handler will always be given the event detail information as its argument.

{heart}
</button>
</section>
</div>
</>
);
};

ChatEntry.propTypes = {
// Fill with correct proptypes
sender: PropTypes.string.isRequired,
body: PropTypes.string.isRequired,
timeStamp: PropTypes.string.isRequired,
id: PropTypes.number.isRequired,
liked: PropTypes.bool.isRequired,
onLiked: PropTypes.func,
Comment on lines +35 to +40

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👍 The id, sender, body, timeStamp, and liked props are always passed (they're defined explicitly in the data and also provided in the test) so we can (and should) mark them isRequired, as you did.

The remaining props were up to you, and the tests don't know about them. As a result, using isRequired causes a warning when running any tests that only pass the known props.

To properly mark any other props isRequired, we would also need to update the tests to include at least dummy values (such as an empty callback () => {} for the like handler) to make the proptype checking happy.

Alternatively, for any props that we leave not required, we should also have logic in our component to not try to use the value if it's undefined.

};

export default ChatEntry;
39 changes: 39 additions & 0 deletions src/components/ChatLog.jsx
Original file line number Diff line number Diff line change
@@ -0,0 +1,39 @@
import './ChatLog.css';
import ChatEntry from './ChatEntry';
import PropTypes from 'prop-types';

const ChatLog = ({entries, onLiked}) => {
const chatEntryComponents = entries.map((chatEntry) => {

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Nice use of map to convert from the message data into ChatEntry components. We can perform this mapping storing the result into a variable we use in the JSX result as you did here (components are functions, so we can run JS code as usual before we reach the return, and even sometimes have multiple return statements with different JSX), we could make a helper function that we call as part of the return, or this expression itself could be part of the return JSX, which I often like since it helps me see the overall structure of the component, though can make debugging a little more tricky. But any of those approaches will work fine.

return (
<ChatEntry
key={chatEntry.id}

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👍 The key attribute is important for React to be able to detect certain kinds of data changes in an efficient manner. We're also using the id for our own id prop, so it might feel redundant to pass both, but one is for our logic and one is for React internals (we can't safely access the key value in any meaningful way).

sender={chatEntry.sender}
body={chatEntry.body}
timeStamp={chatEntry.timeStamp}
id={chatEntry.id}
liked={chatEntry.liked}
onLiked={onLiked}>
</ChatEntry>
);
});

return (
<div className='chat-log'>
{chatEntryComponents}
</div>
);
};

ChatLog.propTypes = {
entries: PropTypes.arrayOf(
PropTypes.shape({
sender: PropTypes.string.isRequired,
body: PropTypes.string.isRequired,
timeStamp: PropTypes.string.isRequired,
id: PropTypes.number.isRequired,
liked: PropTypes.bool.isRequired,
})).isRequired,
onLiked: PropTypes.func,
};

export default ChatLog;