var myObj = new Object();

Object.preventExtensions(myObj);

myObj.name = "Smith";

​

console.log(myObj.name);

​

​

(function () {

    "use strict";

​

    try {

        var strictObj = new Object();

        Object.preventExtensions(strictObj);

        strictObj.name = "Smith";

        console.log(strictObj.name);

​

    } catch (ex) {

        console.log("Strict mode Exception ::: " + ex);

    }

})();