如何在JavaScript ES5中从数组返回重复的对象计数

Question

我使用下面的代码来获取数组中重复对象的计数。

我正在通过一个包含组的表进行查询，这很复杂。我将组及其复杂性传递给一个对象。我有重复的条目，比如

[
    {group: A, complexity: Simple},
    {group: A, complexity: Complex},
    {group: A, complexity: Simple},
    {group: B, complexity: Simple},
    {group: A, complexity: Medium}
]

我需要如下所示的重复数

[
    {group: A, complexity: Simple}: 2,
    {group: A, complexity: Complex}: 1,
    {group: B, complexity: Simple}: 1,
    {group: C, complexity: Medium}: 1
] 

​

var data = {};
var app = [];

for(let i=0; i<=2; i++){
  var fName = "Ram";
  var lName = "Krishna";
data = { "ID": fName, "Status": lName };
app.push(data);
}

var call = JSON.stringify(duplicate(app));
console.log("call: " + call);


function duplicate(app)
{
var counts = {};

for(var i =0; i < app.length; i++)
{
 
  var ab = JSON.stringify(app[i]);
    if (counts[ab])
    {
       counts[ab] += 1;
    }else{
       counts[ab] = 1;
    }
} 
return counts;

}

​

我得到了下面的输出

call: {"{\"ID\":\"Ram\",\"Status\":\"Krishna\"}":3}

我所期待的

call: {"{"ID":"Ram","Status":"Krishna"}":3}

有谁能帮我一下吗？

Answer 1

使用以下方法，可能会有进一步的改进：

const getDuplicates = arr => { 
  const dupCount = arr.reduce((acc, curr) => {
    acc[curr] = acc[curr] ? acc[curr] + 1 : 1;
    return acc;
  }, {});
  return Object.entries(dupCount).filter(([k, v]) => v > 1).map(([k, v]) => k)
}