script4.js

/* This file simulates how to access a native json file*/
var output = document.getElementById('output');
var ajaxhttp = new XMLHttpRequest(); // creates a js object with required functiionality
var url = "json.json"; // the exteranal json file


ajaxhttp.open("GET", url, true); // access the json file
ajaxhttp.setRequestHeader("content-type", "application/json"); // value sent over to the server, indicating 
                                                      // what type of content the browser expects to receive
/* 
      readyState - represents communication with an external file
      status - a flag used to indicate the success or failure of communication
*/

ajaxhttp.onreadystatechange = function(){
  if(ajaxhttp.readyState == 4 && ajaxhttp.status == 200){
    var jcontent = ajaxhttp.responseText;
    console.log( jcontent); // displays the response text 
    console.log("ajaxhttp = ", ajaxhttp); // displays the object
  }
};

ajaxhttp.send(null); // currently sending nothing back
output.innerHTML ="nothing";