Question

我有一个对象数组列表，我只想返回数组中的最后7个对象。帮助请

我尝试使用，过滤，映射和查找，但无法获得预期的输出结果

var welcomeMessage = [{
    from: "Clement",
    text: "Welcome to Freeborn chat system!",
    id: 0
  },
  {
    from: "mark",
    text: "Hello",
    id: 1
  },
  {
    from: "clement",
    text: "welcome",
    id: 2
  },
  {
    from: "mark",
    text: "long time",
    id: 3
  },
  {
    from: "clement",
    text: "yeah, indeed",
    id: 4
  },
  {
    from: "mark",
    text: "real good to be hear",
    id: 5
  },
  {
    from: "clement",
    text: "you looking good",
    id: 7
  },
  {
    from: "mark",
    text: "Hello",
    id: 8
  },
  {
    from: "clement",
    text: "welcome",
    id: 9
  }
]

const messages = [welcomeMessage]

function latestMessage(messages, search) {
  let search = rquest.body;
  let messages = messages.length - 7
  const messages.filter(message => {
    return message
  })
}

Answer 1

您可以将Array#slice与结尾处的负索引一起使用。

var welcomeMessage = [{ from: "Clement", text: "Welcome to Freeborn chat system!", id: 0 }, { from: "mark", text: "Hello", id: 1 }, { from: "clement", text: "welcome", id: 2 }, { from: "mark", text: "long time", id: 3 }, { from: "clement", text: "yeah, indeed", id: 4 }, { from: "mark", text: "real good to be hear", id: 5 }, { from: "clement", text: "you looking good", id: 7 }, { from: "mark", text: "Hello", id: 8 }, { from: "clement", text: "welcome", id: 9 }, { from: "mark", text: "long time", id: 10 }, { from: "clement", text: "yeah, indeed", id: 11 }];

console.log(welcomeMessage.slice(-6));

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

Answer 2

让lastSeven = welcomeMessage.slice（-7）;

Answer 3

以上答案是正确的，也是最佳解决方案，但是如果您需要使用过滤器，则可以执行以下操作：

const items = welcomeMessage.filter((obj, index) => {
    const arrayLength = welcomeMessage.length;
    const wantedItems = 6;
    return arrayLength - index <= wantedItems;
});

我想从数组中获取最后6个对象

3 个答案: