你想通過(guò)一個(gè) for 循環(huán)來(lái)迭代數(shù)組、對(duì)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(dǎo)(comprehension)來(lái)代替 for 循環(huán),這些推導(dǎo)最終會(huì)被編譯成 JavaScript 中等價(jià)的 for 循環(huán)。