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5 changes: 4 additions & 1 deletion project-docs/wave-01.md
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,10 @@

**Learn Topics: React Components and Props required for this wave**

Update the `ChatEntry` and `App` components to display a single chat message bubble with the message text and relative timestamp, plus the sender's name above it.
Update the `ChatEntry` and `App` components to display a
single chat message bubble with the message text and
relative timestamp, plus
the sender's name above it.

A good way to test this code as you write it would be to take the first chat message from the [JSON data file](../src/data/messages.json) and use it as the data for the `ChatEntry` component.

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22 changes: 19 additions & 3 deletions src/App.jsx
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@@ -1,14 +1,30 @@
import './App.css';
import ChatLog from './components/ChatLog';
import chatData from './data/messages.json';
import { useState } from 'react';

const App = () => {
const [entries, setEntries] = useState(chatData);
const toggleLike = (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.

const updatedEntries = entries.map((entry) => {

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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 (entry.id === id) {
return { ...entry, liked: !entry.liked };
} else {
return entry;
}
});
setEntries(updatedEntries);

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In this case, calculating the next version of the message data using the current state variable and passing that updated version to the state setter shouldn't cause any problems, but we still generally prefer using the callback style of setters. Using that approach, we pass a function to the setter whose parameter will receive the latest state value, and which returns the new value to use for the state.

    setEntries(entries => entries.map(entry => {
      if (entry.id === id) {
        return {...entry, liked: !entry.liked};
      } else {
        return entry;
      };
    }));

};
const likeCount = entries.reduce((total, entry) => {
return entry.liked ? total + 1 : total;
}, 0);
Comment on lines +18 to +20

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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.

One way that we can make using reduce a little more understandable for other programmers reading our code would be to give the custom function that we pass to reduce a descriptive name.

const sumLikes = (total, entry) => {
  return entry.liked ? total + 1 : total;
};

const likeCount = entries.reduce(sumLikes, 0);

return (
<div id="App">
<header>
<h1>Application title</h1>
<h1>{likeCount} ❤️s</h1>
Comment on lines -7 to +24

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👀 Notice in the example screenshots that in addition to the like counts, there was a header listing the conversation participants that we wanted to show, even if it weren't calculated dynamically.

</header>
<main>
{/* Wave 01: Render one ChatEntry component
Wave 02: Render ChatLog component */}
<ChatLog entries={entries} onLikeToggle={toggleLike} />
</main>
</div>
);
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24 changes: 18 additions & 6 deletions src/components/ChatEntry.jsx
Original file line number Diff line number Diff line change
@@ -1,20 +1,32 @@
import './ChatEntry.css';
import TimeStamp from './TimeStamp';
import PropTypes from 'prop-types';
// import { useState } from 'react';

const ChatEntry = () => {
const ChatEntry = (props) => {

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ChatEntry uses a single props param, but ChatLog uses a destructured object. Personally, I prefer the destructured style, since it makes the expected component attributes a bit more clear. And it's fine to use a mixture of styles in this project, but in general, try to pick one style or the other.

const heart = props.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 handleLikeClick = () => {
props.onLikeToggle(props.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.

};
return (
<div className="chat-entry local">
<h2 className="entry-name">Replace with name of sender</h2>
<h2 className="entry-name">{props.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>
<p>{props.body}</p>
<p className="entry-time"><TimeStamp time={props.timeStamp}/></p>

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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!

<button className="like" onClick={handleLikeClick}>{heart}</button>

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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.

</section>
</div>
);
};

ChatEntry.propTypes = {
// Fill with correct proptypes
id: PropTypes.number.isRequired,
sender: PropTypes.string.isRequired,
body: PropTypes.string.isRequired,
timeStamp: PropTypes.string.isRequired,
liked: PropTypes.bool,
onLikeToggle: PropTypes.func.isRequired,
Comment on lines +24 to +29

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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.

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. If you didn't see those warnings when running the tests, be sure to also try running the terminal npm test since the warnings are more visible.

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;
36 changes: 36 additions & 0 deletions src/components/ChatLog.jsx
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@@ -0,0 +1,36 @@
import PropTypes from 'prop-types';
import ChatEntry from './ChatEntry';
import './ChatLog.css';

const ChatLog = ({entries, onLikeToggle}) => {
const chatComponents = entries.map((entry) => {

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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={entry.id}
id={entry.id}
Comment on lines +9 to +10

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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={entry.sender}
body={entry.body}
timeStamp={entry.timeStamp}
liked={entry.liked}
onLikeToggle={onLikeToggle}
/>
);
});

return <div className="chat-log">{chatComponents}</div>;
};

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

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We can make the liked value required, since even in the base tests a value is being supplied.

})
).isRequired,
onLikeToggle: PropTypes.func.isRequired

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Similar to the props for ChatEntry here, the entries prop is included in the tests, but the like toggle is not, resulting in prop warnings (unless we update the tests to reflect our custom props).

Again, if we were to leave this as not required so as to avoid the test warnings, we'd want to be sure that all the script logic in our component worked properly even in the absence of this value.

};

export default ChatLog;