Javascript counting number of objects in object

Question

I have an object something like:

Object {0=Object, 1=Object, 2=Object} // Output from console.log(obj.Data);

But there is no way for me to count the number of objects in the object and then get the attribute value from the subobjects.

I attempted

console.log(obj.Data[0].length); // It does not work

console.log(obj.Data.length); // It does not work

This is a little tricky for me. I'm hoping you can assist.

Answer 1

The simplest approach to accomplish this while maintaining outstanding performance and compatibility with both old and modern browsers is to add Lo-Dash or Underscore in your website.

Then you may use _.size(object) or _.keys() (object).

length

You might try this with your obj.Data:

console.log( _.size(obj.Data) );

or:

console.log( _.keys(obj.Data).length );

Both Lo-Dash and Underscore are good libraries that you would find quite handy in your programming. (They are quite similar; Lo-Dash is a newer version with certain advantages.)

You may also include the following method in your code, which just runs over the object's properties and counts them:

function ObjectLength( object ) {
    var length = 0;
    for( var key in object ) {
        if( object.hasOwnProperty(key) ) {
            ++length;
        }
    }
    return length;
};

You can test this with:

console.log( ObjectLength(obj.Data) );

However, with newer browsers, such code is not as quick as it might be. You may use: for a version that is significantly quicker in newer browsers but still works in older ones.

function ObjectLength_Modern( object ) {
    return Object.keys(object).length;
}

function ObjectLength_Legacy( object ) {
    var length = 0;
    for( var key in object ) {
        if( object.hasOwnProperty(key) ) {
            ++length;
        }
    }
    return length;
}

var ObjectLength =
    Object.keys ? ObjectLength_Modern : ObjectLength_Legacy;

and as before, test it with:

console.log( ObjectLength(obj.Data) );

In contemporary browsers, this code utilises Object.keys(object).length; in older versions, it goes back to counting in a loop.

But if you're going to do all of this effort, I'd advocate utilising Lo-Dash or Underscore instead to reap the benefits of those libraries.