javascript - Summarizing data for JSON - 


{id:1, val:'author', hits:1},  {id:1, val:'author', hits:2},  {id:1, val:'reviewer', hits:1},  {id:2, val:'author', hits:100},  {id: 1, val:'author', hits:5}

etc.

i want aggregates data (can javascript, jquery, or angular filters single loop)

{id: 1, author:3, reviewer:1, hits:9 } {id: 2, author:1, reviewer:0, hits:100}

breaking head on bit now!!

one possible approach:

var source = [  {id:1, val:'author', hits:1},   {id:1, val:'author', hits:2},   {id:1, val:'reviewer', hits:1},  {id:2, val:'author', hits:100},   {id: 1, val:'author', hits:5}  ];  var grouped = source.reduce(function(dict, el, i, arr) {   var obj = dict[el.id];   if (!obj) {     obj = {       id: el.id,       author: 0,       reviewer: 0,       hits: 0     };     dict.__arr.push(obj);     dict[el.id] = obj;   }   obj[el.val]++;   obj.hits += el.hits;   return === arr.length - 1? dict.__arr : dict; }, {__arr:[]});

demo. often, when need group items criteria, use array.reduce dictionary object organize grouping process. in case, it's bit more complicated because need resulting array single loop; dictionary object supplied specific property ('__arr') that's filled while dictionary constructed. in end (checked i === arr.length - 1) array given out result of .reduce.


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