javascript - 按组分组数组并按位置排序

Question

我有一个数组。我需要按组对这个数组进行分组并按位置排序。我想创建一个新数组，其中组名作为键，值作为按组分组的排序数组，但效果不佳。我该怎么做？

a = [
    {id:1,name:'qw'group:'C',name:'hite',position:'1'},
    {id:2,name:'qwe'group:'B',name:'ite',position:'2'},
    {id:3,name:'qwer'group:'A',name:'ite',position:'3'},
    {id:4,name:'qer'group:'D',name:'te',position:'4'},
    {id:5,name:'wer'group:'C',name:'whit',position:'5'},
    {id:6,name:'er'group:'B',name:'whi',position:'6'},
]

function groupDo(array){                
  var groups = [];
  for (var i in array){
    groups[array[i].group] = array[i].group;
  }
  for (var i in array){
    if (groups[array[i].group] == array[i].group){
      groups[array[i].group] = array[i];
    }
   }
}

Answer 1

这是一个简单直接的答案:

var sortByPosition = function(obj1, obj2) {
  return obj1.position - obj2.position;
};

var arr = [
  { id: 1, name: 'qw', group: 'C', name: 'hite', position: '1' },
  { id: 2, name: 'qwe', group: 'B', name: 'ite', position: '2' },
  { id: 3, name: 'qwer', group: 'A', name: 'ite', position: '3' },
  { id: 4, name: 'qer', group: 'D', name: 'te', position: '4' },
  { id: 5, name: 'wer', group: 'C', name: 'whit', position: '5' },
  { id: 6, name: 'er', group: 'B', name: 'whi', position: '6' },
];

var grouped = {};

for (var i = 0; i < arr.length; i += 1) {
  if(!grouped[arr[i].group]) {
    grouped[arr[i].group] = [];
  }
  grouped[arr[i].group].push(arr[i]);
}

for (var group in grouped) {
  grouped[group] = grouped[group].sort(sortByPosition);
}

console.log(grouped);

当你想做这样的事情时，通常建议使用像 lodash 这样的实用程序库。或 underscore.js ，这样您就不必“重新发明轮子”。下面是使用其中一个库的样子:

var arr = [
  { id: 1, name: 'qw', group: 'C', name: 'hite', position: '1' },
  { id: 2, name: 'qwe', group: 'B', name: 'ite', position: '2' },
  { id: 3, name: 'qwer', group: 'A', name: 'ite', position: '3' },
  { id: 4, name: 'qer', group: 'D', name: 'te', position: '4' },
  { id: 5, name: 'wer', group: 'C', name: 'whit', position: '5' },
  { id: 6, name: 'er', group: 'B', name: 'whi', position: '6' },
];

var grouped = _.groupBy(arr, 'group');

for (var group in grouped) {
  _.sortBy(grouped[group], 'position');
}

console.log(grouped);