从对象数组中提取具有另一个属性等于给定值的项目的属性值数组

Question

下面给出了一个数组。 我想获取该数组中团队为红色的每个成员的用户名！

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"]
  },

];

我试过这段代码：

const colorTeam = array.filter(teams=>teams.team === 'red');
console.log('teamColor:', username);

它没有用！

Answer 1

与filter() + map() （源数组上的两次传递）相反，可以使用Array.prototype.reduce()来实现单次传递（如果输入数组足够大，这可能会带来一定的性能增益，或经常执行此类过滤）：

 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"]}], redTeamNames = array.reduce((acc, {username, team}) => (team == 'red' && acc.push(username), acc), []) console.log(redTeamNames)

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Answer 2

如果这是你想要的？ 首先我们用team === red过滤对象，然后我们 map 数组只包含username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 colorTeam = array.filter(teams=>teams.team === 'red').map(user=>user.username); console.log('teamColor:', colorTeam);

Answer 3

用户Array.filter后跟Array.map ：

 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"]}]; let result = array.filter(({team}) => team === "red").map(({username}) => username) console.log(result)

Answer 4

在一行中：

let newArray = array.filter((el) => el.team==="red" ? el : "").map((el) => el.username);

首先，过滤具有名为“red”的团队属性的对象，然后使用 map 方法仅获取用户名属性。