JSFiddle - React, Tailwind, and code Playground

JavaScript

/* SIMPLE OBJECT */
personObj = new Object();
personObj.name = "david"
personObj.age = 25;

/* COMPLEX OBJECT */
var employees = { "accounting" : [   // accounting is an array in employees.
                                    { "firstName" : "John",  // First element
                                      "lastName"  : "Doe",
                                      "age"       : 23 },
                                    
                                    { "firstName" : "Mary",  // Second Element
                                      "lastName"  : "Smith",
                                      "age"       : 32 }
                                  ], // End "accounting" array.                                  
                  "sales"       : [ // Sales is another array in employees.
                                    { "firstName" : "Sally", // First Element
                                      "lastName"  : "Green",
                                      "age"       : 27 },
                                    
                                    { "firstName" : "Jim",   // Second Element
                                      "lastName"  : "Galley",
                                      "age"       : 41 }
                                  ] // End "sales" Array.
                } // End Employees

/* TEST SIMPLE OBJECT */
var start = (new Date).getTime();
for (i = 0; i < 10000000; ++i) {
var x = 'name' in personObj;
}
var diff = (new Date).getTime() - start;
alert ("'in' took " + diff);
///////////////////
var start = (new Date).getTime();
for (i = 0; i < 10000000; ++i) {
var x = personObj.hasOwnProperty('name');
}
var diff = (new Date).getTime() - start;
alert ("'hasOwnProperty' took " + diff);
/* END TEST SIMPLE OBJECT*


/* TEST COMPLEX OBJECT */
var start = (new Date).getTime();
for (i = 0; i < 10000000; ++i) {
var x = 'sales' in employees ;
}
var diff = (new Date).getTime() - start;
alert ("'in' took " + diff);
///////////////////
var start = (new...