## 問題 Problem 你想使用數組來做值交換。 You want to use an array to swap variables. ## 方法 Solution 使用CoffeeScript的[解構賦值](http://jashkenas.github.com/coffee-script/#destructuring)語法： Use CoffeeScript’s?[destructuring assignment](http://jashkenas.github.com/coffee-script/#destructuring)?syntax: ~~~ a = 1 b = 3 [a, b] = [b, a] a # => 3 b # => 1 ~~~ ## 討論 Discussion 解構賦值允許交換兩個值，而無需使用中間變量。 Destructuring assignment allows swapping two values without the use of a temporary variable. 當迭代數組需要保證迭代最短的數組時，這個特性相當有用： This can be useful when traversing arrays and ensuring iteration only happens over the shortest one: ~~~ ray1 = [ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 ] ray2 = [ 5, 9, 14, 20 ] intersection = (a, b) -> [a, b] = [b, a] if a.length > b.length value for value in a when value in b intersection ray1, ray2 # => [ 5, 9 ] intersection ray2, ray1 # => [ 5, 9 ] ~~~