Question

42

How to count JavaScript array objects?

rated 0 times [ 47] [ 5] / answers: 1 / hits: 109138 / 14 Years ago, thu, april 22, 2010, 12:00:00

When I have a JavaScript object like this:

var member = {

    mother: {

        name : Mary,

        age : 48

    },

    father: {

        name : Bill,

        age : 50

    },

    brother: {

        name : Alex,

        age : 28

    }

}

How to count objects in this object?!

I mean how to get a counting result 3, because there're only 3 objects inside: mother, father, brother?!

If it's not an array, so how to convert it into JSON array?

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ronans

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3 Years ago

answered 14 Years ago isaacvalentinn · Accepted Answer

That's not an array, is an object literal, you should iterate over the own properties of the object and count them, e.g.:

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;

}



objectLength(member); // for your example, 3

The hasOwnProperty method should be used to avoid iterating over inherited properties, e.g.

var obj = {};

typeof obj.toString; // function

obj.hasOwnProperty('toString'); // false, since it's inherited