JSFiddle - React, Tailwind, and code Playground

JavaScript

var data1 = '{"resourceType": "Bundle", "entry": [{"foo": 123, "test":"foo"},{"foo": 456, "test":"abc"}]}';
var data2 = '{"resourceType": "Bundle", "entry": [{"foo": 789, "test":"bar"},{"foo": 120, "test":"def"}]}';

var json1 = JSON.parse(data1);
var json2 = JSON.parse(data2);

var obj = $.extend(true, {},json1,json2);
//var obj = $.merge( $.merge( [], json1 ), json2 )
console.log(obj);