JSFiddle - React, Tailwind, and code Playground

JavaScript

var listA = [{name: "Mike", exercisedateandtime: 1299233593000, exercise: "Jumping Jacks"}, 
{name: "Mike", exercisedateandtime: 1299237012000, exercise: "Running"}];


var listB = [{name: "Charles", exercisedateandtime: 1299233712000, exercise: "Swimming"},
{name: "Charles", exercisedateandtime: 1299233831000, exercise: "Swimming"},
{name: "Charles", exercisedateandtime: 1299240620000, exercise: "Swimming"}];

var listC = [{name: "William", exercisedateandtiem: 1299237611000, exercise:"Motor Boating"},
{name: "William", exercisedateandtime: 1299237320000,exercise: "Fishing"},
{name: "William", exercisedateandtime: 1299305420000,exercise: "Cycling"}];
              
              
var listD = listB.concat(listA,listC);
console.log(listD);
listD.sort(function(a,b){return a.exercisedateandtime - b.exercisedateandtime});
console.log(listD);