javascript - 从对象中切片属性并进行计数

Question

是否可以从对象数组中切片单个属性，例如

[{"name":"Bryan","id":016, "counter":0}, {"name":"John","id":04, "counter":2}, {"name":"Alicia","id":07, "counter":6}, {"name":"Jenny","id":015, "counter":9}, {"name":"Bryan","id":016, "counter":0}, {"name":"Jenny","id":015, "counter":9}, {"name":"John","id":04, "counter":2}, {"name":"Jenny"    ,"id":015, "counter":9}];

我试图从每个对象中切片 name 并计算相同元素的数量(有 3 个名为 Jenny 的对象)，以实现以下结构:

[{"name":"Bryan","Number":2},
{"name":"John","Number":2},
{"name":"Alicia","Number":1},
{"name":"Jenny","Number":3}]

Answer 1

您想忽略已经存在的 id 和 counter 属性吗？

您可以创建一个对象来跟踪唯一名称，并最终转换回数组:

var data = [{"name": "Bryan",  "id": 016,  "counter": 0}, {  "name": "John",  "id": 04,  "counter": 2}, {  "name": "Alicia",  "id": 07,  "counter": 6}, {  "name": "Jenny",  "id": 015,  "counter": 9}, {  "name": "Bryan",  "id": 016,  "counter ": 0}, {  "name": "Jenny",  "id": 015,  "counter ": 9}, {  "name": "John",  "id": 04,  "counter": 2}, {  "name": "Jenny",  "id": 015,  "counter": 9}];

var result = data.reduce(function(result, item) {
  if (!result[item.name]) {
    result[item.name] = {
      name: item.name,
      counter: 0
    };
  }

  result[item.name].counter += 1;
  
  return result;
}, {});

console.log(Object.keys(result).map(function(key) { return result[key] }));