将Object.keys用于对象数组

Question

I use Object.keys to do some key assignation to my arrays of object. But it returned unique object for each iteration, so my 4 items became 2. Any way to avoid that?

 var cityIdmap = {}; var bpidmap = { '7': { cityid: 2, bpid: 7, name: 'Puduraya', time: '+00:00', sbpid: 50169 }, '11': { cityid: 1, bpid: 11, name: 'Golden Mile Tower', time: '+00:00', sbpid: 50172 }, '12': { cityid: 2, bpid: 12, name: 'Berjaya Times Square', time: '+00:00', sbpid: 50171 }, '66': { cityid: 1, bpid: 66, name: 'Textile Centre', time: '+00:00', sbpid: 50170 } }; Object.keys(bpidmap).forEach(function(item) { var bp = bpidmap[item]; cityIdmap[bp.cityid] = {}; cityIdmap[bp.cityid][bp.bpid] = bp; }); document.write(JSON.stringify(cityIdmap)); 

Answer 1

Add check that the object has already been initialized:

Object.keys(bpidmap).forEach(function(item) {
  var bp = bpidmap[item];
  if (typeof cityIdmap[bp.cityid] === 'undefined') cityIdmap[bp.cityid] = {};
  cityIdmap[bp.cityid][bp.bpid] = bp;
});

Answer 2

You can use array in cityIdmap[bp.cityid] instead object

var cityIdmap = {};
var bpidmap = {
  '7': {
    cityid: 2,
    bpid: 7,
    name: 'Puduraya',
    time: '+00:00',
    sbpid: 50169
  },
  '11': {
    cityid: 1,
    bpid: 11,
    name: 'Golden Mile Tower',
    time: '+00:00',
    sbpid: 50172
  },
  '12': {
    cityid: 2,
    bpid: 12,
    name: 'Berjaya Times Square',
    time: '+00:00',
    sbpid: 50171
  },
  '66': {
    cityid: 1,
    bpid: 66,
    name: 'Textile Centre',
    time: '+00:00',
    sbpid: 50170
  }
};

Object.keys(bpidmap).forEach(function(item) {
  var bp = bpidmap[item];
  cityIdmap[bp.cityid] = cityIdmap[bp.cityid] || []; //use array instead of object
  var temp = {};
  temp[bp.bpid] = bp;
  cityIdmap[bp.cityid].push(temp);
});