Javascript: Merge Objects By Key

I have an array of objects that looks like this: var countries = [ {id: SWE, value: 5}, {id: DE, value:10}, {id: SWE, anotherValue: 11}, {id: DE, anotherValue: 15}

Solution 1:

try this:

functionmergeById(a){
  var obj={};
  
  a.forEach(function(e){
    if(e && e.id){
      obj[e.id] = obj[e.id] || {};    
      for(var _k in e) obj[e.id][_k] = e[_k]
    }
  });       
  
  returnObject.keys(obj).map(function (key) {return obj[key]});
}

var countries = [
    {id: 'SWE', value: 5},
    {id: 'DE', value:10},
    {id: 'SWE', anotherValue: 11},
    {id: 'DE', anotherValue: 15}
]
document.write(JSON.stringify(mergeById(countries)))