JSFiddle - React, Tailwind, and code Playground

JavaScript

var obj1 = {
   a: 'test1',
   b: 'test2' 
};

var obj2 = {
   2: 'test1',
   1: 'test2' 
};
// max 32bit unsigned is 2,147,483,647
var obj3 = {
   2147483649: 'test1',
   2147483648: 'test2' 
};
// max 64bit unsigned is 9,223,372,036,854,775,807
var obj4 = {
   9223372036854770: 'test1',
   9223372036854768: 'test2',
};

// != number < 2,147,483,647, order is not changed
console.log(Object.keys(obj1));
// < 2,147,483,647, order is changed
console.log(Object.keys(obj2));
// > 2,147,483,647, order is not changed in Firefox, but changed in Chrome
console.log(Object.keys(obj3));
// > 9,223,372,036,854,775,807, order is not changed in neither Firefox or Chrome
console.log(Object.keys(obj4));