有没有什么对象属性来提取javascript中的嵌套键？

Question

我试图从这个对象的对象中仅提取团队名称，但无法做到这一点

我已经尝试过Object.keys(data)，但它只显示比赛的年份，我也尝试过Object.values(data)，但它显示的输出中既有球队名称，也有与之相关的值。

{ '2008': 
   { 'Chennai Super Kings': 9,
     'Delhi Daredevils': 7,
     'Royal Challengers Bangalore': 4,
     'Kolkata Knight Riders': 5,
     'Rajasthan Royals': 13,
     'Kings XI Punjab': 10,
     'Deccan Chargers': 2,
     'Mumbai Indians': 7 },
  '2009': 
   { 'Royal Challengers Bangalore': 9,
     'Delhi Daredevils': 10,
     'Deccan Chargers': 9,
     'Chennai Super Kings': 8,
     'Kolkata Knight Riders': 3,
     'Rajasthan Royals': 6,
     'Kings XI Punjab': 7,
     'Mumbai Indians': 4 },
  '2010': 
   { 'Mumbai Indians': 11,
     'Delhi Daredevils': 7,
     'Kolkata Knight Riders': 6,
     'Deccan Chargers': 8,
     'Royal Challengers Bangalore': 8,
     'Chennai Super Kings': 9,
     'Rajasthan Royals': 6,
     'Kings XI Punjab': 4 } }

Answer 1

如果你使用的是普通的JS (没有句点、下划线等)，你可以得到这样的团队列表

var obj = {/* your object here */};

// for browsers that have flat() support
var onlyTeams = Object.values(obj).map(Object.keys).flat()

// for browsers without flat() support
var onlyTeams = Object.values(obj).map(Object.keys).reduce((acc, val) => acc.concat(val), []);

如果你想对它们进行重复数据删除，你可以这样做

var dedupedTeams = Array.from(new Set(onlyTeams))

Answer 2

由于团队名称位于嵌套对象中，因此应在map()中使用Object.keys()

​

var obj = { '2008': 
   { 'Chennai Super Kings': 9,
     'Delhi Daredevils': 7,
     'Royal Challengers Bangalore': 4,
     'Kolkata Knight Riders': 5,
     'Rajasthan Royals': 13,
     'Kings XI Punjab': 10,
     'Deccan Chargers': 2,
     'Mumbai Indians': 7 },
  '2009': 
   { 'Royal Challengers Bangalore': 9,
     'Delhi Daredevils': 10,
     'Deccan Chargers': 9,
     'Chennai Super Kings': 8,
     'Kolkata Knight Riders': 3,
     'Rajasthan Royals': 6,
     'Kings XI Punjab': 7,
     'Mumbai Indians': 4 },
  '2010': 
   { 'Mumbai Indians': 11,
     'Delhi Daredevils': 7,
     'Kolkata Knight Riders': 6,
     'Deccan Chargers': 8,
     'Royal Challengers Bangalore': 8,
     'Chennai Super Kings': 9,
     'Rajasthan Royals': 6,
     'Kings XI Punjab': 4 } }
     
 var teams = Object.values(obj).map(o => Object.keys(o));
 console.log(teams);

​

请注意:如果您在单个数组中的团队，您必须使用flat()。

var teams = Object.values(obj).map(o => Object.keys(o)).flat();

Answer 3

您可以遍历第一级对象，然后遍历它们的键，以获得团队名称：

​

data = { '2008': { 'Chennai Super Kings': 9, 'Delhi Daredevils': 7, 'Royal Challengers Bangalore': 4, 'Kolkata Knight Riders': 5, 'Rajasthan Royals': 13, 'Kings XI Punjab': 10, 'Deccan Chargers': 2, 'Mumbai Indians': 7 }, '2009': { 'Royal Challengers Bangalore': 9, 'Delhi Daredevils': 10, 'Deccan Chargers': 9, 'Chennai Super Kings': 8, 'Kolkata Knight Riders': 3, 'Rajasthan Royals': 6, 'Kings XI Punjab': 7, 'Mumbai Indians': 4 }, '2010': { 'Mumbai Indians': 11, 'Delhi Daredevils': 7, 'Kolkata Knight Riders': 6, 'Deccan Chargers': 8, 'Royal Challengers Bangalore': 8, 'Chennai Super Kings': 9, 'Rajasthan Royals': 6, 'Kings XI Punjab': 4 } }

Object.values(data).forEach(value => {
    Object.keys(value).forEach(token => console.log(token));
});

​

如果您想单独获取每一年的团队名称，请执行以下操作：

​

data = { '2008': { 'Chennai Super Kings': 9, 'Delhi Daredevils': 7, 'Royal Challengers Bangalore': 4, 'Kolkata Knight Riders': 5, 'Rajasthan Royals': 13, 'Kings XI Punjab': 10, 'Deccan Chargers': 2, 'Mumbai Indians': 7 }, '2009': { 'Royal Challengers Bangalore': 9, 'Delhi Daredevils': 10, 'Deccan Chargers': 9, 'Chennai Super Kings': 8, 'Kolkata Knight Riders': 3, 'Rajasthan Royals': 6, 'Kings XI Punjab': 7, 'Mumbai Indians': 4 }, '2010': { 'Mumbai Indians': 11, 'Delhi Daredevils': 7, 'Kolkata Knight Riders': 6, 'Deccan Chargers': 8, 'Royal Challengers Bangalore': 8, 'Chennai Super Kings': 9, 'Rajasthan Royals': 6, 'Kings XI Punjab': 4 } }

Object.values(data).forEach(value => {
    console.log(Object.keys(value));
});

​

要获得多年来唯一的团队名称，请执行以下操作：

​

data = { '2008': { 'Chennai Super Kings': 9, 'Delhi Daredevils': 7, 'Royal Challengers Bangalore': 4, 'Kolkata Knight Riders': 5, 'Rajasthan Royals': 13, 'Kings XI Punjab': 10, 'Deccan Chargers': 2, 'Mumbai Indians': 7 }, '2009': { 'Royal Challengers Bangalore': 9, 'Delhi Daredevils': 10, 'Deccan Chargers': 9, 'Chennai Super Kings': 8, 'Kolkata Knight Riders': 3, 'Rajasthan Royals': 6, 'Kings XI Punjab': 7, 'Mumbai Indians': 4 }, '2010': { 'Mumbai Indians': 11, 'Delhi Daredevils': 7, 'Kolkata Knight Riders': 6, 'Deccan Chargers': 8, 'Royal Challengers Bangalore': 8, 'Chennai Super Kings': 9, 'Rajasthan Royals': 6, 'Kings XI Punjab': 4 } }
var teams = new Set();
Object.values(data).forEach(value => Object.keys(value).forEach(team => teams.add(team)));
console.log(teams)

​