user91579631 user91579631 - 1 month ago 6
Node.js Question

Retain some objects from an array of objects that meets criteria and remove the rest

I have an array of objects in javascript. The contents look like this;

obj_array = [{
"DATA_ID": 1,
"DATA_NAME": "Dim",
"DATA_BB_TYP": 2,
"DATA_MAC": "0158d0045e8fb0",
},
{
"DATA_ID": 3,
"DATA_NAME": "Spre",
"DATA_BB_TYP": 33,
"DATA_MAC": "8e30",
},
{
"DATA_ID": 2,
"DATA_NAME": "Dimb",
"DATA_BB_TYP": 2,
"DATA_MAC": "45e8",
},
{
"DATA_ID": 4,
"DATA_NAME": "Kht1",
"DATA_BB_TYP": 35,
"DATA_MAC": "58d0",
},
{
"DATA_ID": 6,
"DATA_NAME": "Sens",
"DATA_BB_TYP": 34,
"DATA_MAC": "d004",
}
]


I want to retain some objects and remove the rest. If the object property
DATA_BB_TYP
is 2 or 34, the objects will be retained. THe other objects are removed. The outcome of the
obj_array
will look like this;

obj_array_retained =
[{
"DATA_ID": 1,
"DATA_NAME": "Dim",
"DATA_BB_TYP": 2,
"DATA_MAC": "0158d0045e8fb0",
},
{
"DATA_ID": 2,
"DATA_NAME": "Dimb",
"DATA_BB_TYP": 2,
"DATA_MAC": "45e8",
},
{
"DATA_ID": 6,
"DATA_NAME": "Sens",
"DATA_BB_TYP": 34,
"DATA_MAC": "d004",
}
]


I am using node.js v6.91.

EDIT: Someone suggested to me using filter to solve this kind of problem. Answers using filter technique would be most welcomed.

Answer

You can try the below methods 1 and 2:

Method 1: (Using filter)

Note: This will return a new array and won't modify the original array.

var obj_array = [{
            "DATA_ID": 1,
            "DATA_NAME": "Dim",
            "DATA_BB_TYP": 2,
            "DATA_MAC": "0158d0045e8fb0",
        },
        {
            "DATA_ID": 3,
            "DATA_NAME": "Spre",
            "DATA_BB_TYP": 33,
            "DATA_MAC": "8e30",
        },
        {
            "DATA_ID": 2,
            "DATA_NAME": "Dimb",
            "DATA_BB_TYP": 2,
            "DATA_MAC": "45e8",
        },
        {
            "DATA_ID": 4,
            "DATA_NAME": "Kht1",
            "DATA_BB_TYP": 35,
            "DATA_MAC": "58d0",
        },
        {
            "DATA_ID": 6,
            "DATA_NAME": "Sens",
            "DATA_BB_TYP": 34,
            "DATA_MAC": "d004",
        }
    ];

    var retained = [2, 34];

    var new_obj_array = obj_array.filter(function(obj) {
      if(retained.indexOf(obj.DATA_BB_TYP) === -1) {
        return false;
      }
      
      return true;
    });

    console.log(new_obj_array);

Method 2: (Basic version if you intend to use this in browser since filter won't be supported by old browsers)

var obj_array = [{
        "DATA_ID": 1,
        "DATA_NAME": "Dim",
        "DATA_BB_TYP": 2,
        "DATA_MAC": "0158d0045e8fb0",
    },
    {
        "DATA_ID": 3,
        "DATA_NAME": "Spre",
        "DATA_BB_TYP": 33,
        "DATA_MAC": "8e30",
    },
    {
        "DATA_ID": 2,
        "DATA_NAME": "Dimb",
        "DATA_BB_TYP": 2,
        "DATA_MAC": "45e8",
    },
    {
        "DATA_ID": 4,
        "DATA_NAME": "Kht1",
        "DATA_BB_TYP": 35,
        "DATA_MAC": "58d0",
    },
    {
        "DATA_ID": 6,
        "DATA_NAME": "Sens",
        "DATA_BB_TYP": 34,
        "DATA_MAC": "d004",
    }
];

var retained = [2, 34];

for(var i = obj_array.length - 1; i >= 0; i--) {
  var obj = obj_array[i];
  if(retained.indexOf(obj.DATA_BB_TYP) === -1) {
    obj_array.splice(i, 1);
  }
}

console.log(obj_array);