javascript - Lodash:使用最新项目创建新数组

Question

我有一个如下的数组

[{
        "id": "001",
        "name": "A",
        "timestamp_created": "2019-02-27T11:22:19"
    },
    {
        "id": "002",
        "name": "A",
        "timestamp_created": "2019-02-27T11:30:19"
    },
    {
        "id": "003",
        "name": "B",
        "timestamp_created": "2019-02-27T10:15:19"
    },
    {
        "id": "004",
        "name": "B",
        "timestamp_created": "2019-02-27T11:05:19"
    }
]

我想基于上述数组创建一个新数组，但仅包含最新项目(按项目名称分组)。

 [{
            "id": "002",
            "name": "A",
            "timestamp_created": "2019-02-27T11:30:19"
        },
        {
            "id": "004",
            "name": "B",
            "timestamp_created": "2019-02-27T11:05:19"
        }
    ]

如何结合不同Lodash的功能来实现结果？

有什么建议，请帮助我。

Answer 1

你可以采取Map ，收集所有最新项目(通过检查 timestamp_created)，按 name 分组并获取值。

var data = [{ id: "002", name: "A", timestamp_created: "2019-02-27T11:30:19" }, { id: "003", name: "B", timestamp_created: "2019-02-27T10:15:19" }, { id: "004", name: "B", timestamp_created: "2019-02-27T11:05:19" }, { id: "001", name: "A", timestamp_created: "2019-02-27T11:22:19" }],
    result = Array.from(data
        .reduce(
            (m, o) => m.has(o.name) && m.get(o.name).timestamp_created > o.timestamp_created
               ? m
               : m.set(o.name, o),
            new Map
        )
        .values()
    );
    
console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }