Update Data in a List without Mutations

how do you get the multiple cursor to be placed on the test.skip locations without manually placing it there with 'option-click' ?

Joel,

In atom, you can trigger the select-next function with cmd+D. If your cursor is in the middle of a word, the first cmd+D will select the current word, then each subsequent use of cmd+D will select the next occurrence of that word. If you want to select something more involved that isn't automatically selected with the first cmd+D, use the mouse or other keys to select that entire series of chars, then you can use cmd+D to select that combination elsewhere in the file.

Hope this helps!

I am getting an error when I run npm test

 FAIL  src/lib/todoHelpers.test.js
  ● Test suite failed to run

    Couldn't find preset "es2015" relative to directory "/home/johndoe"

Can anyone help me out. I don't think it's an issue with the tut, just me messing things up...

Iain,

Are you running the tests from your home directory instead of the project directory? That's what it looks like at a glance. If that's not it, I might need some more info to help you work this out. Let me know.

I tried writing the updateTodo helper myself before seeing how it was done in the video, and I came up with:

export const updateTodo = (list, updated) =>
  list.map(todo => todo.id === updated.id ? updated : todo);

I was surprised to see something very different in the video:

export const updateTodo = (list, updated) => {
  const updatedIndex = list.findIndex(item => item.id === updated.id)
  return [
    ...list.slice(0, updatedIndex),
    updated,
    ...list.slice(updatedIndex+1)
  ]
}

Is there any benefit to the longer version using slice, or gotchas with using map?

Seb,

Using map here is fine and there are no gotchas that I'm aware of, nor can I think of any specific benefits to the more verbose approach.

I mainly used the spread operator here to remain consistent with the way I was handling addTodo, toggleTodo and removeTodo.

I like the use of map here personally and have used this approach before, though I suppose one could argue that map implies a transformation is being applied to each item in the list.

The bottom line here is that either way is fine and both accomplish the same goal so I say use the style you prefer.

Hope this helps.

Very good course so far. I'm learning some basic React, loving it so far. I like how the course gives also some introduction to TDD and Immutability, something I currently struggle to get into. Props to you!

kefkef5,

I'm really glad you're getting so much out of it! Thanks for the kind feedback :)

I just could not get this part. What is this code returning? Aren't we returning whole list here?

export const updateTodo = (list, updated) => {
  const updatedIndex = list.findIndex(item => item.id === updated.id)
  return [
    ...list.slice(0, updatedIndex),
    updated,
    ...list.slice(updatedIndex+1)
  ]
}

why ...list.slice(updatedIndex+1) ? I tested without it and it really did not made any difference