Length of a JavaScript object

Question

I have a JavaScript object. Is there a built-in or accepted best practice way to get the length of this object?

const myObject = new Object();
myObject["         


        

Answer 1

Here is a completely different solution that will only work in more modern browsers (Internet Explorer 9+, Chrome, Firefox 4+, Opera 11.60+, and Safari 5.1+)

See this jsFiddle.

Setup your associative array class

/**
 * @constructor
 */
AssociativeArray = function () {};

// Make the length property work
Object.defineProperty(AssociativeArray.prototype, "length", {
    get: function () {
        var count = 0;
        for (var key in this) {
            if (this.hasOwnProperty(key))
                count++;
        }
        return count;
    }
});

Now you can use this code as follows...

var a1 = new AssociativeArray();
a1["prop1"] = "test";
a1["prop2"] = 1234;
a1["prop3"] = "something else";
alert("Length of array is " + a1.length);