在coffeescript数组中查找重复值的最简单方法

Question

我是coffeescript的新手。请帮帮我。

如何在数组中找到重复的值？

var arr = ['manager','manager','employee','manager',
           'director','employee','manager','operatives'];

在这种情况下，它应该返回[＆＃39;经理＆＃39;，＆＃39;员工＆＃39;]。

Answer 1

试试这个：

    findDuplicates = (array) ->
        keys = {}
        for value in array
            keys[value] ?= 0
            keys[value]++
        (key for key, count of keys when count > 1)

    arr = ['manager','manager','employee','manager', 'director','employee','manager','operatives']
    console.log findDuplicates(arr)

Answer 2

使用filter，更轻松。

arr = ['manager','manager','employee','manager','director','employee','manager','operatives'];

filtered = arr.filter (x, i, self) ->
  self.indexOf(x) == i && i != self.lastIndexOf(x)

console.log filtered # => ['manager', 'employee']