我得到了这种类型的数组，并且我只想按一列进行分组（名）从整个数组，

[
   {
     first_name: "Apurv",
     date: "2018-01-22",
     is_present: "1", 
   }
   {
     first_name: "Lucky",
     date: "2018-01-22",
     is_present: "0", 
   }
   {
     first_name: "Apurv",
     date: "2018-01-20",
     is_present: "0", 
   }
   {
     first_name: "Lucky",
     date: "2018-01-20",
     is_present: "1", 
   }
]

那么我怎样才能按这个数组从“成分"?

var data = [
   {
     first_name: "Apurv",
     date: "2018-01-22",
     is_present: "1", 
   },
   {
     first_name: "Lucky",
     date: "2018-01-22",
     is_present: "0", 
   },
   {
     first_name: "Apurv",
     date: "2018-01-20",
     is_present: "0", 
   },
   {
     first_name: "Lucky",
     date: "2018-01-20",
     is_present: "1", 
   }
];

var groupByName = {};

data.forEach(function (a) {
    groupByName [a.first_name] = groupByName [a.first_name] || [];
    groupByName [a.first_name].push({ date: a.date, is_present: a.is_present });
});

console.log(groupByName);