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极客学院团队出品 · 更新于 2018-07-18 13:00:41

For 循环

问题

你想通过一个 for 循环来迭代数组、对象或范围。

解决方案

# for(i = 1; i<= 10; i++)
x for x in [1..10]
# => [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 ]

# To count by 2
# for(i=1; i<= 10; i=i+2)
x for x in [1..10] by 2
# => [ 1, 3, 5, 7, 9 ]

# Perform a simple operation like squaring each item.
x * x for x in [1..10]
# = > [1,4,9,16,25,36,49,64,81,100]

讨论

CoffeeScript 使用推导(comprehension)来代替 for 循环,这些推导最终会被编译成 JavaScript 中等价的 for 循环。