Errata for CoffeeScript

#49739: 2,2 Scope: Where you see 'em, first example

Book says:

age = 99
reincarnate = -> age = 0 reincarnate()
console.log "I am #{age} years old"

As you’d probably expect, the output is this:
I am 0 years old

Here's my result:

$ node -v
v0.6.15

$ coffee
coffee> age = 99
99

coffee> reincarnate = -> age = 0
[Function]

coffee> reincarnate()
0

coffee> console.log "I am #{age} years old"
I am 99 years old

--
I get 99 not 0.
--Greg Clarke

#48606: With Node.js version v0.6.0 and CoffeScript version 1.2.0 , when this snippet is executed :
count = 0
incrementCount = -> count++

incrementCount() it returns 0 instead of 1 why is that ? you can even type console.log "count is now #{incrementCount()}" and gets "count is now 0" ?--Gilles MATHURIN

#49328: Book says:

setName 'Lulu'
console.log name # 'Lulu'
console.log @name # undefined

But when I run the code, I don't get "undefined" for the last line.

setName = (name) -> @name = name

setName 'Lulu'
console.log name
console.log @name

Results in:

Lulu
Lulu

--Dan Livingston

#50199: Where slices are described, the following example is given:
coffee> ['this', 'that', 'the other'][1..]
['that', 'the other']

The answer should the whole array, that is:
['this', 'that', 'the other'] and not just the first and the last element.--Andrei Fecioru

#47363: germanToEnglish: {ja: 'yes', nein: 'no'}
should be
germanToEnglish = {ja: 'yes', nein: 'no'}

Also

germanToEnglish[ja]?
should be
germanToEnglish['ja']?--Nick G

#50146: randomLetter() uses the following to generate a random number:

randomNumber = Math.ceil(Math.random() * totalTiles)

However, Math.random() returns a random number between 0 (inclusive)
and 1 (exclusive). Using Math.ceil then gives you a possible outcome in
the range 0..totalTiles - a total of totalTiles + 1 possiblities, with 0
having a lower probability than all others (only 0 will return this).

Given the following loop starts with x = 1, the range for randomNumber
must be 1..totalTiles. So the proper call should be:

randomNumber = Math.floor(Math.random() * totalTiles) + 1

The other option would be to start with x = 0, then use:

randomNumber = Math.floor(Math.random() * totalTiles)

--Brian D. Burns

#48019: tribble1 = new Tribble
tribble2 = new Tribble
tribble1.die()
tribble2.die()
Tribble.makeTrouble()

actually shows me "Trouble! Trouble!"

But this is fixed after changing

console.log ('Trouble!' for i in [1..@count]).join(' ')

To:

console.log ('Trouble!' for i in [0...@count]).join(' ')

which then echoes nothing which is what I expected.

Regards,
Swaroop
www.swaroopch.com--Swaroop

#49470: The drawTiles function iterates through y before x in the repo

Instead of:
for x in [0...blah]
for y in [0...blah]

...the jq5x5.coffee does repo code is different to the book (not allowed to post links so couldn't reference it)
for y in [0...blah]
for x in [0...blah]--Vlad Ivanovic

#47785: For the 5x5 demo game, the Player.coffee listing does not indicate that the "scoreMove" function is to be included in this file (as within the supplied code) and instead implies that it should be placed in the console.coffee file.--donald hutchison

#47958: game = new Game

This won't work since a) the game file is not required (it is in the sample code but that's not mentioned in the text) and b) there is absolutely no mention of the whole Game.coffee file in the text.

The reader will thus need to reverse-engineer the url scheme of example code to get to the Game.coffee file to actually find the code.--Jarkko Laine

#47959: If we run the app as suggested in the beginning of the page, it will lead to an error, because socket.io is not installed. The issue here is that the socket.io part is already included in the long code listing on page 98 (and then again later on page 100). In a similar vein, the connect code on pages 99-100 is already included in the earlier long listing mentioned above.

Also, running the app did not work if the packages were installed globally, they had to be installed locally for me (node 0.7). --Jarkko Laine

#48888: Section 2.2, scope example not working as expected -- text says I should expect a function to modify the value of a variable first declared before, then referenced within the function. But it doesn't seem to work that way. Output from my console:

[tharrison@macbook:~/coffee] coffee -v
CoffeeScript version 1.2.0
[tharrison@macbook:~/coffee] node -v
v0.6.6
[tharrison@macbook:~/coffee] coffee
coffee> age = 99
99
coffee> reincarnate = -> age = 0
[Function]
coffee> reincarnate()
0
coffee> console.log "I am #{age} years old"
I am 99 years old
undefined
coffee>

The text says I should expect age to be 0, not 99. I wouldn't actually expect that -- in most other worlds, variables within functions have their own scope and would thus behave as I am seeing here (age is 99). I am not exactly whether the error is in the text, or if CoffeeScript is behaving differently than it used to. Or somethin' :-)--Tom Harrison

#50425: Trying x ?= y on coffeescript.org results in:

"the variable "x" can't be assigned with ?= because it has not been defined."
(coffeescript.org/#try:x%20%3F%3D%20y%0A)--Andreas Kemkes

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