javascript - Using linq.js, I need to group by 2 fields and produce summary -

i have json

var obj = [{projectname:"test1", catname: "subtest1, marks1: 25, marks2: 45}, {projectname:"test1", catname: "subtest1", marks1: 45, marks2: 45}, {projectname:"test1", catname: "subtest2", marks1: 25, marks2: 45} {projectname:"test1", catname: "subtest2", marks1: 15, marks2: 25}, {projectname:"test2", catname: "subtest1", marks1: 35, marks2: 45} {projectname:"test2", catname: "subtest2", marks1: 20, marks2: 55} {projectname:"test2", catname: "subtest2", marks1: 25, marks2: 65}  ] 

i need group projectname , catname , sum each marks achieve result below

result = [{projectname:"test1", catname: "subtest1", marks1: 70, marks2: 90}, {projectname:"test1", catname: "subtest2", marks1: 40, marks2: 70} .....] 

please help.

in plain javascript, use hash table reference same group , collect wanted data.

var data = [{ projectname: "test1", catname: "subtest1", marks1: 25, marks2: 45 }, { projectname: "test1", catname: "subtest1", marks1: 45, marks2: 45 }, { projectname: "test1", catname: "subtest2", marks1: 25, marks2: 45 }, { projectname: "test1", catname: "subtest2", marks1: 15, marks2: 25 }, { projectname: "test2", catname: "subtest1", marks1: 35, marks2: 45 }, { projectname: "test2", catname: "subtest2", marks1: 20, marks2: 55 }, { projectname: "test2", catname: "subtest2", marks1: 25, marks2: 65 }],      groups = ['projectname', 'catname'],      values = ['marks1', 'marks2'],      grouped = data.reduce(function (hash) {          return function (r, a) {              var key = groups.map(function (k) { return a[k]; }).join('|');              if (!hash[key]) {                  hash[key] = {};                  groups.foreach(function (k) { hash[key][k] = a[k]; });                  values.foreach(function (k) { hash[key][k] = 0; });                  r.push(hash[key]);              }              values.foreach(function (k) { hash[key][k] += a[k]; });              return r;          };      }(object.create(null)), []);    console.log(grouped);

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version linq.js

var data = [{ projectname: "test1", catname: "subtest1", marks1: 25, marks2: 45 }, { projectname: "test1", catname: "subtest1", marks1: 45, marks2: 45 }, { projectname: "test1", catname: "subtest2", marks1: 25, marks2: 45 }, { projectname: "test1", catname: "subtest2", marks1: 15, marks2: 25 }, { projectname: "test2", catname: "subtest1", marks1: 35, marks2: 45 }, { projectname: "test2", catname: "subtest2", marks1: 20, marks2: 55 }, { projectname: "test2", catname: "subtest2", marks1: 25, marks2: 65 }],      result = enumerable.from(data)          .groupby(              null,              null,              "{ projectname: $.projectname, catname: $.catname, marks1: $$.sum('$.marks1'), marks2: $$.sum('$.marks2') }",              "$.projectname + ' ' + $.catname"          )          .toarray();    console.log(result);

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