javascript - how to group objects in an array -


i have array of objects , want group objects on basis of 2 keys

var arr = [    {"name": "apple", "id": "apple_0","c":'20'},    {"name": "dog",   "id": "dog_1","c":'10'},    {"name": "apple", "id": "apple_0","c":'30'},   {"name": "dog",   "id": "dog_1","c":'10'}, ];

and expecting result as

var final = [    {"name": "apple", "id": "apple_0","c":'50'},    {"name": "dog",   "id": "dog_1","c":'20'} ];

the scenario - want group object on basis of name , id. if name , id found in final array make sum of c.

i tried this:

var final = []; for(var = 0; i<arr.length; i++){     var obj = {};     obj = arr[i];     for(var j = 0; j<final.length; j++){         if((obj[name] !== final[j].name) && (obj[id] !== final[j].id)){           final.push(obj)         }else{             //addition of key `c` in existing object in `final` array          }     } }

but inner loop not working , hanging system due continuous loop execution.

please let me know how fix or other logic final result.

here solution using hash table , #reduce() function - see demo below:

var arr = [{"name": "apple", "id": "apple_0","c":'20'},{"name": "dog",   "id": "dog_1","c":'10'}, {"name": "apple", "id": "apple_0","c":'30'},{"name": "dog",   "id": "dog_1","c":'10'}];    var result = arr.reduce(function(hash){    return function(p,c){      if(hash[c.id])        hash[c.id].c = +hash[c.id].c + +c.c      else {        hash[c.id] = hash[c.id] || c;        p.push(hash[c.id]);      }      return p;    }  }(object.create(null)), []);    console.log(result);
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