JSFiddle - React, Tailwind, and code Playground

JavaScript

var event1 = {id: 1, title: 'ABC', start: '10'};
var event2 = {id: 2, title: 'ABC', start: '10'};
var event3 = {id: 3, title: 'DEF', start: '12'};
var event4 = {id: 4, title: 'DEF', start: '20'};

var a=[];
a.push(event1);
a.push(event2);
a.push(event3);
a.push(event4);

var b = [];

$.each(a, function(index, event) {
    var events = $.grep(b, function (e) {
        return event.title === e.title &&
            event.start === e.start;
    });
    if (events.length === 0) {
      b.push(event);
    }
});

console.log(b);