coffeescript - CoffeeScript 循环效率

Question

super 简单的coffeescript问题

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

这行得通。但我知道，使用 candy 语法，可能有甚至更像 CoffeeScript 的方式来编写它。有没有办法不使用 i 来写这个？

Answer 1

规范的 CoffeeScript 方法是使用 for comprehension，它将返回一个数组:

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

或者，在一行中:

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

参见 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.