javascript - 从数组中的对象获取特定值

Question

考虑到以下包含多个对象的数组，我尝试在一个数组中获取特定值。说得委婉点，我想提取“红色”团队中人员的名字。

// 
    const array = [
      {
        username: "Mike",
        team: "red",
        score: 20,
     items: ["bat", "book", "gloves"]
  },
  {
    username: "Moe",
    team: "blue",
    score: 30,
    items: ["cellphone", "backpack", "cards"]
  },
  {
    username: "Ellie",
    team: "red",
    score: 15,
    items: ["ball", "canteen", "crayon"]
  },
  {
    username: "little_joe",
    team: "green",
    score: 1,
    items: ["book", "pencil"]
  },

];

//using filter method :

const filterArray=array.filter((num)=>{ if (num.team==="red" ){ return num.username}});
console.log(filterArray);

//result : an array including two objects full of unwanted values.

---

我应该怎么做才能获得一个只有所需值(而不是两个大对象)的数组？

我正在尝试获取这样的数组:(2)►[迈克,艾莉]

Answer 1

一种方法是使用 Array.prototype.filter 和 Array.prototype.map。但是，首选方法是使用 Array.prototype.reduce，因为它会更有效率。

像这样:

const array = [{
    username: "Mike",
    team: "red",
    score: 20,
    items: ["bat", "book", "gloves"]
  },
  {
    username: "Moe",
    team: "blue",
    score: 30,
    items: ["cellphone", "backpack", "cards"]
  },
  {
    username: "Ellie",
    team: "red",
    score: 15,
    items: ["ball", "canteen", "crayon"]
  },
  {
    username: "little_joe",
    team: "green",
    score: 1,
    items: ["book", "pencil"]
  },

];

const newArray = array.reduce((n, val) => {
  if(val.team == "red") n.push(val.username);
  return n;
}, []);

console.log(newArray);