## 問題 Problem 你想給一個數組去重。 You want to remove duplicate elements from an array. ## 方法 Solution ~~~ Array::unique = -> output = {} output[@[key]] = @[key] for key in [0...@length] value for key, value of output [1,1,2,2,2,3,4,5,6,6,6,"a","a","b","d","b","c"].unique() # => [ 1, 2, 3, 4, 5, 6, 'a', 'b', 'd', 'c' ] ~~~ ## 討論 Discussion JavaScript中有很多中`unique`方法的實現。這里的這個實現基于”The fastest method to find unique items in array”，在[這里](http://www.shamasis.net/2009/09/fast-algorithm-to-find-unique-items-in-javascript-array/)可以找到。 There are many implementations of the?`unique`?method in JavaScript. This one is based on “The fastest method to find unique items in array” found?[here](http://www.shamasis.net/2009/09/fast-algorithm-to-find-unique-items-in-javascript-array/). **注意：**?盡管這在常見的語言，比如說Ruby中很常見，但是在JavaScript中擴展原生對象往往被成是不好的實踐。(參看：?[Maintainable JavaScript: Don’t modify objects you don’t own](http://www.nczonline.net/blog/2010/03/02/maintainable-javascript-dont-modify-objects-you-down-own/);?[Extending built-in native objects. Evil or not?](http://perfectionkills.com/extending-built-in-native-objects-evil-or-not/))。 **Note:**?Although it’s quite common in languages like Ruby, extending native objects is often considered bad practice in JavaScript (see:?[Maintainable JavaScript: Don’t modify objects you don’t own](http://www.nczonline.net/blog/2010/03/02/maintainable-javascript-dont-modify-objects-you-down-own/);?[Extending built-in native objects. Evil or not?](http://perfectionkills.com/extending-built-in-native-objects-evil-or-not/)).