如何根据字典中的不同值返回键的值[重复]答案

【问题标题】：How can I return the value of a key based on a different value in a dictionary [duplicate]如何根据字典中的不同值返回键的值[重复]
【发布时间】：2022-01-17 13:56:59
【问题描述】：

const array = [
  {
    username: "john",
    team: "red",
    score: 5,
    items: ["ball", "book", "pen"]
  },
  {
    username: "becky",
    team: "blue",
    score: 10,
    items: ["tape", "backpack", "pen"]
  },
  {
    username: "susy",
    team: "red",
    score: 55,
    items: ["ball", "eraser", "pen"]
  },
  {
    username: "tyson",
    team: "green",
    score: 1,
    items: ["book", "pen"]
  },

];

我有上面的数组。我已经过滤了团队红色的用户。有没有办法只返回团队红色的所有用户的用户名，而不是返回整个数据条目？所以输出应该是“[约翰，苏西]”。到目前为止我有这个代码。

const filterArray = array.filter(user3 => {
  return user3.team === "red";
})

【问题讨论】：

标签： javascript arrays dictionary filter

【解决方案1】：

您可以map 过滤后的数组只包含用户名属性。

const array=[{username:"john",team:"red",score:5,items:["ball","book","pen"]},{username:"becky",team:"blue",score:10,items:["tape","backpack","pen"]},{username:"susy",team:"red",score:55,items:["ball","eraser","pen"]},{username:"tyson",team:"green",score:1,items:["book","pen"]}];


const filterArray = array.filter(user3 => {
  return user3.team === "red";
})

const onlyNames = filterArray.map(u => u.username)

console.log(onlyNames)

【讨论】：

【解决方案2】：

由于filter 方法的结果是一个数组，您可以将map 覆盖过滤后的数组并仅提取username 属性，如下所示：

const array = [ { username: "john", team: "red", score: 5, items: ["ball", "book", "pen"] }, { username: "becky", team: "blue", score: 10, items: ["tape", "backpack", "pen"] }, { username: "susy", team: "red", score: 55, items: ["ball", "eraser", "pen"] }, { username: "tyson", team: "green", score: 1, items: ["book", "pen"] },];

const filterArray = array.filter(({team}) => team === "red").map(({username}) => username)

console.log(filterArray)

【讨论】：