JSFiddle - React, Tailwind, and code Playground

JavaScript

function count(obj) {
    var i = 0;
    for (var key in obj) {
        i++;
    };
    console.log(i);
};
            

var a = { a: 1, b: 2 };
count(a); // 2

var b = function () {};
count(b); // 0
            
var c = [1, 2, 3];
count(c); // 3
            
var d = [];
d[100] = 1;
count(d); // 1