Monica --- Ocelots #6
Conversation
| const [numberLikes, setNumberLikes] = useState(0); | ||
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| const updateChatEntry = (chatToUpdate) => { | ||
| const chats = chatEntries.map((entry) => { | ||
| if(entry.id === chatToUpdate.id){ | ||
| setNumberLikes(chatToUpdate.liked ? numberLikes+1 : numberLikes-1) | ||
| return chatToUpdate; | ||
| } | ||
| return entry; | ||
| }); | ||
| setChatEntries(chats); | ||
| }; |
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Since the liked status of a message lives in the chatEntries data we should avoid holding an extra piece of state that we need to manually keep in sync. We can use a higher order function like array.reduce to take our list of messages and reduce it down to a single value (our like count).
// This could be returned from a helper function
// totalLikes is a variable that accumulates a value as we loop over each entry in chatEntries
const likesCount = chatEntries.reduce((totalLikes, currentMessage) => {
// If currentMessage.liked is true add 1 to totalLikes, else add 0
return (totalLikes += currentMessage.liked ? 1 : 0);
}, 0); // The 0 here sets the initial value of totalLikes to 0| <header> | ||
| <h1>Application title</h1> | ||
| <div className='applicationTitle'> | ||
| <h1>Chat between <span className='green'>Vladimir</span> and <span className='blue'>Estragon</span> </h1> |
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This is a little bit of personal taste, but I suggest dropping the spans to new, indented lines to make it easier to see at a glance what is nested inside the h1.
| const updateClickState = () => { | ||
| onUpdateChat({ | ||
| id, | ||
| sender, | ||
| body, | ||
| timeStamp, | ||
| liked : !liked | ||
| }) | ||
| } |
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I would consider passing the id of the message clicked to onUpdateChat and having the App code handle the new object creation. When ChatEntry creates the new object for the App state, it takes some responsibility for managing those contents. If we want the responsibility of managing the state to live solely with App, we would want it to handle defining the new message object.
This made me think of a related concept in secure design for APIs. Imagine we had an API for creating and updating messages, and it has an endpoint /<msg_id>/like meant to update a true/false liked value. We could have that endpoint accept a body in the request and let the user send an object with data for the message's record (similar to passing a message object from ChatEntry to App), but the user could choose to send any data for those values. If the endpoint only takes in an id and handles updating the liked status for the message itself, there is less opportunity for user error or malicious action.
| if(sender === 'Vladimir'){ | ||
| entryClass = 'local'; | ||
| }else{ | ||
| entryClass = 'remote'; | ||
| } |
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This is a great place for a javascript ternary operator:
const entryClass = (sender === 'Vladimir') ? 'local' : 'remote';| const ChatLog = ({entries, onUpdateChat}) => { | ||
| const messages = entries.map((message, index) => { | ||
| return( | ||
| <section key = {index}> |
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If the messages all have unique ids, then we could use those values for the key over generating and using indices.
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| ChatLog.propTypes = { | ||
| entries: PropTypes.arrayOf( | ||
| PropTypes.shape({ |
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Really nice use of PropTypes.
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