如何根據物件的值將物件陣列拆分為另一個陣列？-有解無憂

我需要根據玩家 ID 將資料從陣列中分離出來。我得到的資料庫是這樣的：

var database =[
 {
  player: 1,
  level: 1,
  score: 20
 },
 {
  player: 2,
  level: 1,
  score: 25
 },
 {
  player: 3,
  level: 1,
  score: 7
 },
 {
  player: 1,
  level: 2,
  score: 25
 },
 {
  player: 2,
  level: 2,
  score: 7
 }
]

一點一點地，包含新玩家的新物件將被添加，舊物件將消失，因為資料庫限制為 40 個條目。這意味著資料庫是動態變化的。

我的目標是根據玩家 ID 將物件推送到新的陣列中。所以結果必須是這樣的：

var player1 = [
 {
  player: 1,
  level: 1,
  score: 20
 },
 {
  player: 1,
  level: 2,
  score: 25
 }
]

var player2 = [
 {
  player: 2,
  level: 1,
  score: 25
 },
 {
  player: 2,
  level: 2,
  score: 7
 }
]

var player3 = [
 {
  player: 3,
  level: 1,
  score: 7
 }
]

uj5u.com熱心網友回復：

首先，您可以將陣列轉換為物件以改進訪問，然后您可以將物件屬性分配給變數：

const database = [
 {
  player: 1,
  level: 1,
  score: 20
 },
 {
  player: 2,
  level: 1,
  score: 25
 },
 {
  player: 3,
  level: 1,
  score: 7
 },
 {
  player: 1,
  level: 2,
  score: 25
 },
 {
  player: 2,
  level: 2,
  score: 7
 }
];

const { player1, player2, player3 } = database.reduce((acc, el) => {
  if (!('player'   el.player in acc)) acc['player'   el.player] = [el];
  else acc['player'   el.player].push(el);
  return acc
}, {});

console.log(player1, player2, player3);

uj5u.com熱心網友回復：

雖然可以用動態名稱創建全域變數，但不能用動態名稱創建非全域變數，而且全域環境已經足夠擁擠，創建一堆新的全域變數不是最佳實踐。

相反，使用一個Map：

const playerArrays = new Map();
for (const entry of database) {
    const key = `player${entry.player}`;
    const array = playerArrays.get(key);
    if (!array ) {
        // Haven't seen this one yet, add a new array
        playerArrays.set(key, [entry]);
    } else {
        // We have the array, add to it
        array.push(entry);
    }
}

然后你通過使用playerArrays.get("player1")等等來獲得一個單獨的陣列。

現場示例：

顯示代碼片段

var database = [{
    player: 1,
    level: 1,
    score: 20
  },
  {
    player: 2,
    level: 1,
    score: 25
  },
  {
    player: 3,
    level: 1,
    score: 7
  },
  {
    player: 1,
    level: 2,
    score: 25
  },
  {
    player: 2,
    level: 2,
    score: 7
  }
];

const playerArrays = new Map();
for (const entry of database) {
    const key = `player${entry.player}`;
    const array = playerArrays.get(key);
    if (!array ) {
        // Haven't seen this one yet, add a new array
        playerArrays.set(key, [entry]);
    } else {
        // We have the array, add to it
        array.push(entry);
    }
}
console.log("player1:", playerArrays.get("player1"));

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

轉載請註明出處，本文鏈接：https://www.uj5u.com/qiye/361592.html

標籤：javascript 数组目的

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