Combine two arrays using undercoreJS

app.js

var app = angular.module('plunker', []);

app.controller('MainCtrl', function($scope) {
  $scope.name = 'World';
  var a = [{id:456, name:'sojuz'},
         {id:751, name:'sputnik'},
         {id:56, name:'arianne'}];

  var b = [{id:751, weight:5800},
         {id:456, weight:2659},
         {id:56, weight:6700}];
         
  var c = _.map(a, function(element) {
    var weight = _.findWhere(b, { id: element.id });

    return _.extend(element, weight);
    });
    
    console.log(c);
});

Kombiniranje dvije matrice objekata na način da se objekti matrice a prošire sa propertijem weight matrice b gdje je property id isti kao u matrici a