Conversation
…play and connect messages.json in App to render first message
anselrognlie
left a comment
anselrognlie
left a comment
There was a problem hiding this comment.
Looks good! Please review my comments, and let me know if you have any questions. Nice job!
| body: PropTypes.string.isRequired, | ||
| timeStamp: PropTypes.string.isRequired, | ||
| liked: PropTypes.bool.isRequired, | ||
| onLikeToggle: PropTypes.func.isRequired, |
There was a problem hiding this comment.
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.
| <button className="like">🤍</button> | ||
| <p>{body}</p> | ||
| <p className="entry-time"> | ||
| <TimeStamp time={timeStamp} /> |
There was a problem hiding this comment.
Nice use of the supplied TimeStamp. We 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!
| entries: PropTypes.arrayOf( | ||
| PropTypes.shape({ | ||
| id: PropTypes.number.isRequired, | ||
| sender: PropTypes.string.isRequired, | ||
| body: PropTypes.string.isRequired, | ||
| timeStamp: PropTypes.string.isRequired, | ||
| liked: PropTypes.bool.isRequired, | ||
| }) | ||
| ).isRequired, | ||
| onLikeToggle: PropTypes.func.isRequired, |
There was a problem hiding this comment.
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.
| key={entry.id} | ||
| id={entry.id} |
There was a problem hiding this comment.
👍 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).
| import './ChatLog.css'; | ||
|
|
||
| const ChatLog = ({entries, onLikeToggle }) =>{ | ||
| const ChatEntries = entries.map( (entry) => { |
There was a problem hiding this comment.
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 it can make debugging a little more tricky. But any of those approaches will work fine.
| <TimeStamp time={timeStamp} /> | ||
| </p> | ||
| <button className="like" onClick={() => onLikeToggle(id)}> | ||
| {liked ? '❤️' : '🤍'} |
There was a problem hiding this comment.
👍 Nice use of a ternary to pick the emoji to show for the liked status. Consider moving even something small like this to a helper function external to the component, so that the behavior of the emoji-picking logic can be tested easily outside of React.
|
|
||
| const App = () => { | ||
| const [messagesData, setMessagesData] = useState(DATA); | ||
| const toggleLike = (Id) => { |
There was a problem hiding this comment.
Nit: stick with lowercase variable names
| const updatedMessages = messagesData.map((msg) => { | ||
| if (msg.id === Id) { | ||
| return { ...msg, liked: !msg.liked }; | ||
| } else { | ||
| return msg; | ||
| } | ||
| }); | ||
| setMessagesData(updatedMessages); |
There was a problem hiding this comment.
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.
setMessagesData(messagesData => messagesData.map(msg => {
if (msg.id === id) {
return {...msg, liked: !msg.liked};
} else {
return msg;
};
}));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.
| const likedMessages = messagesData.filter((message) => { | ||
| return message.liked === true; | ||
| }); | ||
| const totalLikes = likedMessages.length; |
There was a problem hiding this comment.
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.
Great idea to filter down the data to the liked messages and use the list length as the count. This is a really understandable alternative to the more canonical reduce approach. Compared to reduce, it does make a list potentially as long as the message list, but since we know a similar copying gets done anyway during a render (building the ChatEntry components) on the whole it's not any more costly.
| import TimeStamp from './TimeStamp'; | ||
|
|
||
| const ChatEntry = () => { | ||
| const ChatEntry = ({ id, sender, body, timeStamp, liked, onLikeToggle}) => { |
There was a problem hiding this comment.
👍 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), but I really prefer the glanceability.
2 participants
No description provided.