Question

I have two JSON objects in Javascript, identical except for the numerical values. It looks like this:

var data = {
  "eth0":{"Tx":"4136675","Rx":"13232319"},
  "eth1":{"Tx":"4","Rx":"0"},
  "lo":{"Tx":"471290","Rx":"471290"}
}

var old = {
  "eth0":{"Tx":"4136575","Rx":"13232219"},
  "eth1":{"Tx":"4","Rx":"0"},
  "lo":{"Tx":"471290","Rx":"471290"}
}

One object called “data” has the current values, another object called “old” has the same values from 1 second ago. I’d like to output a JSON object with only the change in values so I can calculate data throughput on the network interfaces.

var throughput = {
  "eth0":{"Tx":"100","Rx":"100"},
  "eth1":{"Tx":"0","Rx":"0"},
  "lo":{"Tx":"0","Rx":"0"}
}

I’m not sure how to go about traversing the JSON data – it could be for any number of interfaces.

Can anyone please lend me a hand? Thanks in advance

Answer 1

You can iterate through the parent and child object properties:

var diff = {};
for(var p in data){
  if (old.hasOwnProperty(p) && typeof(data[p]) == 'object'){
    diff[p] = {};
    for(var i in data[p]){
      if (old[p].hasOwnProperty(i)){
        diff[p][i] = data[p][i] - old[p][i];
      }
    }
  }
}