如何在Node.js中合并两个复杂对象

　　通常情况下，在Node.js中我们可以通过underscore的extend或者lodash的merge来合并两个对象，但是对于像下面这种复杂的对象，要如何来应对呢？

　　例如我有以下两个object：

var obj1 = {
    "name" : "myname",
    "status" : 0,
    "profile": { "sex":"m", "isactive" : true},
    "strarr":["one", "three"],
    "objarray": [
    {
        "id": 1,
        "email": "a1@me.com",
        "isactive":true
    },
    {
        "id": 2,
        "email": "a2@me.com",
        "isactive":false
    }
    ]
};

var obj2 = {
    "name" : "myname",
    "status" : 1,
    "newfield": 1,
    "profile": { "isactive" : false,  "city": "new York"},
    "strarr":["two"],
    "objarray": [
    {
        "id": 1,
        "isactive":false
    },
    {
        "id": 2,
        "email": "a2modified@me.com"
    },
    {
        "id": 3,
        "email": "a3new@me.com",
        "isactive" : true
    }
    ]
};

　　希望合并之后的结果输出成下面这样：

{ name: 'myname',
  status: 1,
  profile: { sex: 'm', isactive: false, city: 'new York' },
  strarr: [ 'one', 'three', 'two' ],
  objarray: 
  [ { id: 1, email: 'a1@me.com', isactive: false },
   { id: 2, email: 'a2modified@me.com', isactive: false },
   { id: 3, email: 'a3new@me.com', isactive: true } ],
newfield: 1 }

 　　通过underscore或者lodash现有的方法我们无法实现上述结果，那只能自己写代码来实现了。

function mergeObjs(def, obj) {
  if (!obj) {
    return def;
  } else if (!def) {
    return obj;
  }

  for (var i in obj) {
    // if its an object
    if (obj[i] != null && obj[i].constructor == Object)
    {
      def[i] = mergeObjs(def[i], obj[i]);
    }
    // if its an array, simple values need to be joined.  Object values need to be remerged.
    else if(obj[i] != null && (obj[i] instanceof Array) && obj[i].length > 0)
    {
      // test to see if the first element is an object or not so we know the type of array we're dealing with.
      if(obj[i][0].constructor == Object)
      {
        var newobjs = [];
        // create an index of all the existing object IDs for quick access.  There is no way to know how many items will be in the arrays.
        var objids = {}
        for(var x= 0, l= def[i].length ; x < l; x++ )
        {
          objids[def[i][x].id] = x;
        }

        // now walk through the objects in the new array
        // if the ID exists, then merge the objects.
        // if the ID does not exist, push to the end of the def array
        for(var x= 0, l= obj[i].length; x < l; x++)
        {
          var newobj = obj[i][x];
          if(objids[newobj.id] !== undefined)
          {
            def[i][x] = mergeObjs(def[i][x],newobj);
          }
          else {
            newobjs.push(newobj);
          }
        }

        for(var x= 0, l = newobjs.length; x<l; x++) {
          def[i].push(newobjs[x]);
        }
      }
      else {
        for(var x=0; x < obj[i].length; x++)
        {
          var idxObj = obj[i][x];
          if(def[i].indexOf(idxObj) === -1) {
             def[i].push(idxObj);
          }
        }
      }
    }
    else
    {
      def[i] = obj[i];
    }
  }
  return def;}

 　　将上述代码稍作改进，我们可以实现在合并过程中将Number类型的值自动相加。

function merge(def, obj) {
    if (!obj) {
        return def;
    }
    else if (!def) {
        return obj;
    }

    for (var i in obj) {
        // if its an object
        if (obj[i] != null && obj[i].constructor == Object)
        {
            def[i] = merge(def[i], obj[i]);
        }
        // if its an array, simple values need to be joined.  Object values need to be re-merged.
        else if(obj[i] != null && (obj[i] instanceof Array) && obj[i].length > 0)
        {
            // test to see if the first element is an object or not so we know the type of array we're dealing with.
            if(obj[i][0].constructor == Object)
            {
                var newobjs = [];
                // create an index of all the existing object IDs for quick access.  There is no way to know how many items will be in the arrays.
                var objids = {}
                for(var x= 0, l= def[i].length ; x < l; x++ )
                {
                    objids[def[i][x].id] = x;
                }

                // now walk through the objects in the new array
                // if the ID exists, then merge the objects.
                // if the ID does not exist, push to the end of the def array
                for(var x= 0, l= obj[i].length; x < l; x++)
                {
                    var newobj = obj[i][x];
                    if(objids[newobj.id] !== undefined)
                    {
                        def[i][x] = merge(def[i][x],newobj);
                    }
                    else {
                        newobjs.push(newobj);
                    }
                }

                for(var x= 0, l = newobjs.length; x<l; x++) {
                    def[i].push(newobjs[x]);
                }
            }
            else {
                for(var x=0; x < obj[i].length; x++)
                {
                    var idxObj = obj[i][x];
                    if(def[i].indexOf(idxObj) === -1) {
                        def[i].push(idxObj);
                    }
                }
            }
        }
        else
        {
            if (isNaN(obj[i]) || i.indexOf('_key') > -1){
                def[i] = obj[i];
            }
            else{
                def[i] += obj[i];
            }
        }
    }
    return def;
}

　　例如有以下两个对象：

var data1 = {
    "_id" : "577327c544bd90be508b46cc",
    "channelId_info" : [
    {
        "channelId_key" : "0",
        "secondLevel_group" : [
        {
            "secondLevel_key" : "568cc36c44bd90625a045c60",
            "sender_group" : [
            {
                "sender_key" : "577327c544bd90be508b46cd",
                "sender_sum" : 40.0
            }
            ],
            "senders_sum" : 40.0
        }
        ],
        "channelId_sum" : 40.0
    }
    ],
    "car_sum" : 40.0
};

var data2 = {
    "_id" : "577327c544bd90be508b46cc",
    "channelId_info" : [
    {
        "channelId_key" : "0",
        "secondLevel_group" : [
        {
            "secondLevel_key" : "568cc36c44bd90625a045c60",
            "sender_group" : [
            {
                "sender_key" : "577327c544bd90be508b46cd",
                "sender_sum" : 20.0
            },
            {
                "sender_key" : "5710bcc7e66620fd4bc0914f",
                "sender_sum" : 5.0
            }
            ],
            "senders_sum" : 25.0
        },
        {
            "secondLevel_key" : "55fbeb4744bd9090708b4567",
            "sender_group" : [
            {
                "sender_key" : "5670f993a2f5dbf12e73b763",
                "sender_sum" : 10.0
            }
            ],
            "senders_sum" : 10.0
        }
        ],
        "channelId_sum" : 35.0
    },
    {
        "channelId_key" : "1",
        "secondLevel_group" : [
        {
            "secondLevel_key" : "568cc36c44bd90625a045c60",
            "sender_group" : [
            {
                "sender_key" : "577327c544bd90be508b46cd",
                "sender_sum" : 20.0
            }
            ],
            "senders_sum" : 20.0
        }
        ],
        "channelId_sum" : 20.0
    }
    ],
    "car_sum" : 55.0
};

　　合并之后的结果如下：

{
    "_id": "577327c544bd90be508b46cc",
    "channelId_info": [
        {
            "channelId_key": "0",
            "secondLevel_group": [
                {
                    "secondLevel_key": "568cc36c44bd90625a045c60",
                    "sender_group": [
                        {
                            "sender_key": "577327c544bd90be508b46cd",
                            "sender_sum": 60
                        },
                        {
                            "sender_key": "5710bcc7e66620fd4bc0914f",
                            "sender_sum": 5
                        }
                    ],
                    "senders_sum": 65
                },
                {
                    "secondLevel_key": "55fbeb4744bd9090708b4567",
                    "sender_group": [
                        {
                            "sender_key": "5670f993a2f5dbf12e73b763",
                            "sender_sum": 10
                        }
                    ],
                    "senders_sum": 10
                }
            ],
            "channelId_sum": 75
        },
        {
            "channelId_key": "1",
            "secondLevel_group": [
                {
                    "secondLevel_key": "568cc36c44bd90625a045c60",
                    "sender_group": [
                        {
                            "sender_key": "577327c544bd90be508b46cd",
                            "sender_sum": 20
                        }
                    ],
                    "senders_sum": 20
                }
            ],
            "channelId_sum": 20
        }
    ],
    "car_sum": 95
}

　　上述代码在日常工作中很有用，值得收藏！