数组对象根据某个属性取出重复的个数

getData() {
  let arrData = [{
    ‘a‘: ‘你‘,
    ‘b‘: ‘1‘,
    ‘c‘: ‘他‘
  }, {
    ‘a‘: ‘他‘,
    ‘b‘: ‘2‘,
    ‘c‘: "它"
  }, {
    ‘a‘: ‘你‘,
    ‘b‘: ‘3‘,
    ‘c‘: "它"
  }, {
    ‘a‘: ‘他‘,
    ‘b‘: ‘4‘,
    ‘c‘: "它"
  }, {
    ‘a‘: ‘它‘,
    ‘b‘: ‘5‘,
    ‘c‘: "它"
  }]
  this.getWordCnt(arr)
},

// 根据等级数据计算重复的个数
getWordCnt (arr) {
  let arrData = arr
  let obj = {}
  for (let i = 0; i < arrData.length; i++) {
    var item = arrData[i].a // a为计算的属性,可换成b,c
    obj[item] = (obj[item] + 1) || 1
  }
  console.log(obj)
  return obj
},