在javascript中对哈希数组进行分组和求和

Question

我有以下哈希数组，并希望将其转换为类似于帖子底部的数组。

var responseData = [
  {deviceType: "Smartphone", deviceCount: 14},
  {deviceType: "Tablet", deviceCount: 11},
  {deviceType: "Notebook", deviceCount: 3},
  {deviceType: "Desktop", deviceCount: 2},
  {deviceType: "Smartphone", deviceCount: 1},
  {deviceType: "Tablet", deviceCount: 10},
  {deviceType: "Notebook", deviceCount: 30},
  {deviceType: "Desktop", deviceCount: 20}
];

function dataMapper(responseData){
  let series = [];
  if(responseData && responseData.length){
  responseData.forEach(function(resource){
  existingElement = series.filter(function (item) {
      return item.deviceType === resource.deviceType;
    });
  if (existingElement) {
    deviceCount = existingElement[0].deviceCount + resource.deviceCount;
    existingElement[0].deviceCount = deviceCount
  }else{
    series[0].push({deviceType: resource.deviceType, y: resource.deviceCount});
  }
    });
  }
  return series
}

console.log(dataMapper(responseData))

我想将其转换为：

var expectedResult = [
    {deviceType: "Smartphone", deviceCount: 15},
    {deviceType: "Tablet", deviceCount: 21},
    {deviceType: "Notebook", deviceCount: 33},
    {deviceType: "Desktop", deviceCount: 22}
];

Answer 1

使用 ES6 Map 和reduce：

const responseData = [{deviceType: "Smartphone", deviceCount: 14},{deviceType: "Tablet", deviceCount: 11},{deviceType: "Notebook", deviceCount: 3},{deviceType: "Desktop", deviceCount: 2},{deviceType: "Smartphone", deviceCount: 1},{deviceType: "Tablet", deviceCount: 10},{deviceType: "Notebook", deviceCount: 30},{deviceType: "Desktop", deviceCount: 20}];

const result = Array.from(
    responseData.reduce( 
        (acc, o) => (acc.get(o.deviceType).deviceCount += o.deviceCount, acc),
        new Map(responseData.map( ({deviceType}) => [deviceType, {deviceType, deviceCount: 0} ] )) 
    ).values()
);

console.log(result);

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