Count JSON objects Javascript

Question

Ok so theres this JSON object:

    jsontext = {"switches":[{"dpid":"00-00-00-00-00-01"},{"dpid":"00-00-00-00-00-02"},{"dpid":"00-00-00-00-00-03"},{"dpid":"00-00-00-00-00-04"},{"dpid":"00-00-00-00-00-05"},{"dpid":"00-00-00-00-00-06"},{"dpid":"00-00-00-00-00-07"}],
"links":[["00-00-00-00-00-01","00-00-00-00-00-05"],["00-00-00-00-00-02","00-00-00-00-00-03"],["00-00-00-00-00-05","00-00-00-00-00-06"],["00-00-00-00-00-05","00-00-00-00-00-07"],["00-00-00-00-00-02","00-00-00-00-00-04"],["00-00-00-00-00-01","00-00-00-00-00-02"]]}

The goal is to count all the dpid objects that exist in it... so I do the following so far:

function objectLength(obj) {
  var result = 0;
  for(var prop in obj) {
    if (obj.hasOwnProperty(prop)) {
    // or Object.prototype.hasOwnProperty.call(obj, prop)
      result++;
    }
  }
  return result;
}

The function that I call to get the amount of dpid's in switches

objectLength(jsontext.switches);

The issue is, when there is only one dpid for switches like this:

jsontext = {"switches":[{"dpid":"00-00-00-00-00-01"}],"links":[]}

it counts 0... it doesn't do anything in the for section... for some reason it assume its empty I guess..?

TL;DR why when only 1 dpid of switches exists is the json object it returns 0..

Cheers!

Answer 1

Since the switches property only seems to contain objects with dpid properties, you don't really have to do anything special to count them. Just do this:

var count = jsontext.switches.length;

Answer 2

You can just do by filtering and using the length property.

var arr = jsontext.switches.filter(function(x){return x.hasOwnProperty('dpid'); });
console.log(arr.length); // number of objects

DEMO