Good Map Usage?

John McElreavey — Wed, 13 Oct 2021 15:09:39 +0000

Do you think this is a good usage of map in terms on readability / performance?

Lets say I'm making a list of notes but only allow 1 per day, You have a list of your notes:

[
{id: 1, date: "2021-10-12", content: "hello world!"}, 
{id: 2, date: "2021-10-13", content: "hope you have a great day!"}
]

We have a text field and a submit button, on click we call upsertNote() which will update the array if it's the same day or will add a new record i.e:

usertNote({date: "2021-10-13", content: "how you get through today!"})
// output:
{id: 2, date: "2021-10-13", content: "how you get through today!"}

usertNote({date: "2021-10-14", content: "Future me!"})
// output:
{id: 3, date: "2021-10-14", content: "future me!"}

Notice how one updates the existing entry and the other creates a new one.

Now lets say we want to add to our existing list. We could do a search on the array for the id but what if we used a Map instead?

Is that better in terms on readability and performace?

e.g.

const toDoList = new Map(originalArray.map((i) => [i.id, i]))
const upsertToDoEntry = usertNote({date: "2021-10-14", content: "Future me!"})

toDoList.set(upsertToDoEntry.id, upsertToDoEntry)

// In our react if we wanted to map these out we'd have to do something like this:
Array.from(toDoList , ([id, toDoEntry]) => (
<span key={id}>{toDoEntry.content}</span>
)

Would you implement it this way? :)

DEV Community: John McElreavey

Good Map Usage?