JSFiddle - React, Tailwind, and code Playground

JavaScript

"use strict"
var obj = {
    test : "1",
    test: "2",
    test: "3"
};
console.log(obj);

//код с https://developer.mozilla.org/ru/docs/Web/JavaScript/Reference/Strict_mode
"use strict";
var o = { p: 1, p: 2 }; // !!! синтаксическая ошибка
console.log(o);