从每个对象的数组中仅获取一个值

Question

我有这个数组

 ["member", "member", "member", "aircraft", "aircraft", "instructor", "instructor"]
0: "member"
1: "member"
2: "member"
3: "aircraft"
4: "aircraft"
5: "instructor"
6: "instructor"

您会帮助我，我怎样才能只获得一名成员，飞机和教练

谢谢