CODEWITHSUNDEEP
coffeescript
Fresheyeball
Fresheyeball

Reputation: 30015

coffee-script loop efficiency

super simple coffeescript question

circles = []
for coordinate, i in coordinates
    circles[i] = new MakeCircle(cnBlue, coordinate.x, coordinate.y, 16, 8, 0, theCanvas.ctx)

This works. But I know that with the syntax candy there is probably and even more coffeescriptish way to write this. Is there a way to write this without using the i?

Upvotes: 3

Views: 296

Answers (4)

Linus Thiel
Linus Thiel

Reputation: 39223

The canonical CoffeeScript way is to use a for comprehension, which will return an array:

circles = for coordinate in coordinates
  new MakeCircle(cnBlue, coordinate.x, coordinate.y, 16, 8, 0, theCanvas.ctx)

Or, on one line:

circles = (new MakeCircle(cnBlue, coordinate.x, coordinate.y, 16, 8, 0, theCanvas.ctx) for coordinate in coordinates)

See Loops and Comprehensions:

Note how because we are assigning the value of the comprehensions to a variable in the example above, CoffeeScript is collecting the result of each iteration into an array.

Upvotes: 4

Ivan Drinchev
Ivan Drinchev

Reputation: 19581

More "coffeescriptish" is writing it on one line :

circles = []
circles[i] = new MakeCircle(cnBlue, coor.x, coor.y, 16, 8, 0, theCanvas.ctx) for coor, i in coordinates

you could remove i when using push

circles = []
mc = (x,y) -> new MakeCircle cnBlue,x,y,16,8,0,theCanvas.ctx
circles.push mc(coor.x,coor.y) for coor in coordinates

Upvotes: 1

Chris Pitman
Chris Pitman

Reputation: 13104

You can always use jQuery map:

circles = jQuery.map(coordinates, 
    (coordinate) -> new MakeCircle(cnBlue, coordinate.x, coordinate.y, 16, 8, 0, theCanvas.ctx)
)

I've never actually written CoffeeScript before, so apologies if that doesn't compile as is. This is definately a more "functional" style way of doing what you want, which I identify with modern javascript.

Upvotes: 0

alex
alex

Reputation: 12265

circles.push(new MakeCircle(cnBlue, coordinate.x, coordinate.y, 16, 8, 0, theCanvas.ctx))

;)

Upvotes: 2

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