Ajax method with javascript

ajax.js

/*global $, jQuery, alert, console, angular*/
/**
 * 
 * @authors Ted Shiu ([email protected])
 * @date    2015-01-09 01:23:09
 * @version $Id$
 */

/**
 * [Ajax basic]
 *
 */
var xhr = new XMLHttpRequest();

xhr.open('GET', 'example.html', true);
xhr.send();
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
        document.getElementById('myDiv').innerHTML = xhr.responseText;
    }
};

/**
 * [Ajax formdata]
 */

var formData = new FormData();
formData.append('str', 'string');
formData.append('num', 123);
var xhr = new XMLHttpRequest();
xhr.open('POST', 'test.php');
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
        document.getElementById('myDiv').innerHTML = xhr.responseText;
    }
};
xhr.send(formData);

/**
 * [Ajax form with application/x-www-form-urlencoded]
 *
 */
var obj = {
        'user': 'ted',
        'password': '123456'
    },
    jsonData;
jsonData = JSON.stringify(obj);
var xhr = new XMLHttpRequest();
xhr.open('POST', 'test.php', true);
xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
        document.getElementById('myDiv').innerHTML = xhr.responseText;
    }
};
xhr.send('json=' + jsonData);

/**
 * [Ajax payload]
 *
 */
var obj = {
        'user': 'ted_shiu',
        'password': '123456'
    },
    jsonData;
jsonData = JSON.stringify(obj);
var xhr = new XMLHttpRequest();
xhr.open('PUT', 'rest.php', true);
xhr.onreadystatechange = function(e) {
    if (xhr.status == 200) {
        document.getElementById('info').innerHTML = xhr.responseText;
    }
};
xhr.send(jsonData);

rest.php

<?php
/**
 * 
 * @authors Your Name ([email protected])
 * @date    2015-01-13 23:39:47
 * @version $Id$
 */

$request = file_get_contents("php://input");
$method = $_SERVER['REQUEST_METHOD'];
print_r($method);
switch($method)
{
    case "PUT":
        print_r(json_decode($request, true));
    break;
    case "GET":
        print_r(json_decode($request, true));
    break;
    case "DELETE":
        print_r(json_decode($request, true));
    break;
    case "POST":
        print_r(json_decode($request, true));
    break;
}