基于两个字段值javascript计算Json数据答案

【问题标题】：count Json data based on two field values javascript基于两个字段值javascript计算Json数据
【发布时间】：2018-06-15 20:41:03
【问题描述】：

在 Angular 组件上的页面加载时，我执行如下获取请求：

 private getData() {
    const url = 'http...';
    const data= this.http.get(url).map( res => res.json());
    return data;
 }

我得到了这个结果：

[
{
id: 1,
type: "science",
action: "on",
name: "title 1",
frequency: 10,
author: null,
},
{
id: 3,
type: "thriller",
action: "off",
name: "Programming",
frequency: 60,
author: 1515202398191,
},
{
id: 4,
type: "article",
action: "pause",
name: "Stories about life",
frequency: 60,
author: 1515202398191,
},
{
id: 5,
type: "science",
action: "on",
name: "Lorem Ipsum",
frequency: 60,
author: 1515202398191,
},
{
id: 6,
type: "science",
action: "off",
name: "Testing",
frequency: 60,
author: 1515202398191,
},
{
id: 8,
type: "science",
action: "on",
name: "Programming",
frequency: 60,
author: 1515202398191,
}
]

在数组里面我有不同的项目，它们都有 type 和 action 有值。我想计算type 和action 具有相同值的项目，这样我就可以获得一些统计数据，例如：

[{"type":"science", action:"on", count: 3},
 {"type":"science", action:"off", count: 1},
 {"type":"thriller", action:"off", count: 1},
 {"type":"article", action:"pause", count: 1},
]

我开始做某事，但我不知道该怎么做

stats: any;
 function countArr(array){
      var array= [];
      var count = 0;
      array.forEach( function(currentItem){

         array.forEach( function(item){
         // check if 
         if(item.type == currentItem.type && item.action == currentItem.action){
                count++;
             }
           });
           var itemJson = {'type':currentItem.type, 'action':currentItem.action, 'count':count };  
           array.push(itemJson);
      });

    }

private getData() {
        const url = 'http...';
        const data= this.http.get(path).map( res => res.json());
        this.stats = countArr(data);
        return data;
     }

【问题讨论】：

使用 reduce/find 组合很容易做到 - 但是您如何期望 {"type":"thriller", action:"on", count: 0}, ...您如何计算输入中没有的内容？例如jsfiddle.net/Lg54er4z/1
我更新了预期的数组，所以基本上我删除了它
啊，没看到修改后的版本：p

标签： javascript angularjs json typescript

【解决方案1】：

试试这个例子 -

var data = [
    {
        id: 1,
        type: "science",
        action: "on",
        name: "title 1",
        frequency: 10,
        author: null,
    },
    {
        id: 3,
        type: "thriller",
        action: "off",
        name: "Programming",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 4,
        type: "article",
        action: "pause",
        name: "Stories about life",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 5,
        type: "science",
        action: "on",
        name: "Lorem Ipsum",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 6,
        type: "science",
        action: "off",
        name: "Testing",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 8,
        type: "science",
        action: "on",
        name: "Programming",
        frequency: 60,
        author: 1515202398191,
    }
];
function getCount() {
    var countData = [];
    data.forEach(function (item, index) {
        var existingItem = countData.find(function (countItem) {
            return item.type === countItem.type &&
                item.action === countItem.action;
        });
        if (existingItem) {
            existingItem.count++;
        }
        else {
            existingItem = {
                type: item.type,
                action: item.action,
                count: 1
            };
            countData.push(existingItem);
        }
    });
    return countData;
}
console.log(getCount());

Typescript 等价物 -

let data: Array<any> = [
    {
        id: 1,
        type: "science",
        action: "on",
        name: "title 1",
        frequency: 10,
        author: null,
    },
    {
        id: 3,
        type: "thriller",
        action: "off",
        name: "Programming",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 4,
        type: "article",
        action: "pause",
        name: "Stories about life",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 5,
        type: "science",
        action: "on",
        name: "Lorem Ipsum",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 6,
        type: "science",
        action: "off",
        name: "Testing",
        frequency: 60,
        author: 1515202398191,
    },
    {
        id: 8,
        type: "science",
        action: "on",
        name: "Programming",
        frequency: 60,
        author: 1515202398191,
    }
]

function getCount() {

    let countData: Array<any> = [];

    data.forEach((item, index) => { 
        let existingItem: any = countData.find((countItem) => {
            return item.type === countItem.type &&
                item.action === countItem.action;
        });
        if (existingItem) {
            existingItem.count++;
        } else {
            existingItem = {
                type: item.type,
                action: item.action,
                count: 1
            };
            countData.push(existingItem);
        }
    });     

    return countData;

}

console.log(getCount());

【讨论】：

【解决方案2】：

你可以这样做：

var res = []
// data is your initial array
data.forEach((item) => {
    const result = res.find(x => x.type === item.type && x.action === item.action)
    if (result) result.count += 1
    else res.push({type: item.type, action: item.action, count: 1})
})

【讨论】：

但我还需要采取行动值，如果它是开、关或任何东西？
与要求的结果完全不同
对不起，我的错误。答案现已修复。