JSFiddle - React, Tailwind, and code Playground

JavaScript

Object.prototype.size = function () {
    var size = 0,
        key;
    for (key in this) {
        if (this.hasOwnProperty(key)) size++;
    }
    return size;
};

var x = {
    one: 1,
    two: 2,
    three: 3
};

if (x.size() === 3) {
    document.write("The size is indeed 3");
}