如何根据多个属性值构造一个新数组？答案

【问题标题】：How can construct a new array based on multiple property values?如何根据多个属性值构造一个新数组？
【发布时间】：2022-12-09 10:12:34
【问题描述】：

我家里有 3 个人 ['John', 'Jane', 'Jack'],

我们跟踪谁打开/关闭了门。

logs = [
  { name: "John", status: "opened" },
  { name: "Jane", status: "opened" },
  { name: "Jack", status: "opened" },
  { name: "Jane", status: "closed" },
  { name: "Jack", status: "closed" },
];

如您所见，只有 2 个人['Jane', 'Jack']正确地打开和关闭了门。

以编程方式，我执行了这 3 个步骤来知道约翰是打开门但从未关闭门的人。

let openers = logs.reduce((acc, log) => {
  if (log.status === "opened") {
    acc.push(log.name);
  }
  return acc;
}, []);

console.log(openers);

let closers = logs.reduce((acc, log) => {
  if (log.status === "closed") {
    acc.push(log.name);
  }
  return acc;
}, []);

console.log(closers);

let result = [];
closers.forEach((closer) => {
  if (openers.includes(closer)) {
    result.push(closer);
  }
});

console.log(result);

我试图一次性完成这些reduce()，但我不太确定。

有人可以帮我改进我得到的东西吗

logs = [
  { name: "John", status: "opened" },
  { name: "Jane", status: "opened" },
  { name: "Jack", status: "opened" },
  { name: "Jane", status: "closed" },
  { name: "Jack", status: "closed" },
];

let openers = logs.reduce((acc, log) => {
  if (log.status === "opened") {
    acc.push(log.name);
  }
  return acc;
}, []);

console.log(openers);

let closers = logs.reduce((acc, log) => {
  if (log.status === "closed") {
    acc.push(log.name);
  }
  return acc;
}, []);

console.log(closers);

let result = [];
closers.forEach((closer) => {
  if (openers.includes(closer)) {
    result.push(closer);
  }
});

console.log(result);

？

【问题讨论】：

标签： javascript ecmascript-6

【解决方案1】：

您可以使用单个 .reduce() 来做到这一点，该 .reduce() 按名称跟踪门的状态：

logs = [
  { name: "John", status: "opened" },
  { name: "Jane", status: "opened" },
  { name: "Jack", status: "opened" },
  { name: "Jane", status: "closed" },
  { name: "Jack", status: "closed" },
];

let statuses = logs.reduce((acc, log) => {
  acc[log.name] = (log.status === 'opened');
  return acc;
}, {});
console.log(statuses);
let culprits = Object.keys(statuses).filter(name => statuses[name]);
console.log(culprits);

输出：

{
  "John": true,
  "Jane": false,
  "Jack": false
}
[
  "John"
]

【讨论】：