你想通過一個 for 循環(huán)來迭代數(shù)組、對象或范圍。
# 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]
CoffeeScript 使用推導(comprehension)來代替 for 循環(huán),這些推導最終會被編譯成 JavaScript 中等價的 for 循環(huán)。