Get object length by checking the key

js-object-length.js

// http://stackoverflow.com/a/18560314
// if condition is for old IE
if (!Object.keys) {
    Object.keys = function (obj) {
        var arr = [],
            key;
        for (key in obj) {
            if (obj.hasOwnProperty(key)) {
                arr.push(key);
            }
        }
        return arr;
    };
}

Object.keys(obj).length;