javascript - get Json Key based on Json Value of an Object which resides in an Json Array -

how key of json resides within array based on value, if value valueb should return mainb

var app = angular.module('myapp', []); app.controller('arraycontroller', function ($scope) {    $scope.mydatas =  [       {         "test1": "value1",         "maina": ""       },       {         "test1": "value2",         "maina": "valueb"       },       {         "test1": "",         "maina": "valuec"       }     ];      $scope.getjsonkey = function(jsonarray, jsonvalue)      {         angular.foreach(jsonarray, function(value, index)          {             if (value.test1 === jsonvalue)              {                 return "test1";             }             if (value.maina === jsonvalue)              {                 return "maina";             }         });     };    console.log($scope.getjsonkey($scope.mydatas, "valueb"));  }); 

can please tell me solution this

here small function should want, long values unique:

var arr=[        {          "test1": "value1",          "maina": "valuea"        },        {          "test2": "value2",          "mainb": "valueb"        },        {          "test3": "value3",          "mainc": "valuec"        }      ]      function getkey(arr, val){      for(var i=0;i<arr.length;i++){          var item= arr[i];          for(var key in item){              if(val === item[key]) return key;          }      }         return null; // not found  }    console.log(getkey(arr, 'valueb')) // mainb