Nested arrays inside JSON object

var myObj, i, j, x = "";
myObj = {
  "name":"John",
  "age":30,
  "cars": [
    {"name":"Ford", "models":["Fiesta", "Focus", "Mustang"]},
    {"name":"BMW", "models":["320", "X3", "X5"]},
    {"name":"Fiat", "models":["500", "Panda"] }
  ]
}

To access nested JSON arrays

for (i in myObj.cars) {
  x += "<h1>" + myObj.cars[i].name + "</h1>";
  for (j in myObj.cars[i].models) {
    x += myObj.cars[i].models[j];
  }
}

The

callback function

name is the same as the

callback

variable passed to the

URL

https://api.github.com/users/yui?callback=handleJSONP_variable

The content returned from the request:

handleJSONP_variable({"meta": {
  "Content-Type": "application/javascript; charset=utf-8",
  "Cache-Control": "public, max-age=60, s-maxage=60",
  "Vary": "Accept",
  "status": 200,
  ...
}, "data": {
  "login": "yui",
  "name": "YUI Library",
  "company": null,
  "blog": "http://yuilibrary.com/",
  "location": "Sunnyvale, CA",
  "email": null,
  "public_repos": 31,
  ...
}})

The code below calls PHP service using AJAX

var xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
  if (this.readyState == 4 && this.status == 200) {
    var myObj = JSON.parse(this.responseText);
    document.getElementById("demo").innerHTML = myObj.name;
  }
};
xmlhttp.open("GET", "demo_file.php", true);
xmlhttp.send();

PHP code that responds to the request

$myArr = array("name"=>"John", "age"=>30, "city"=>"New York");

$myJSON = json_encode($myArr);

echo $myJSON;

JS script below creates

<script>

element and fills with the

JSON

retrieved from a server

<script>

var obj, dbParam, xmlhttp, myObj, x, txt = "";
obj = { table: "customers", limit: 20 };
dbParam = JSON.stringify(obj);
xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
  if (this.readyState == 4 && this.status == 200) {
    myObj = JSON.parse(this.responseText);
    txt += "<select>"
    for (x in myObj) {
      txt += "<option>" + myObj[x].name;
    }
    txt += "</select>"
    document.write(txt);
  }
};
xmlhttp.open("POST", "json_demo_html_table.php", true);
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send("x=" + dbParam);

</script>

Creates

<select>

element using

document.createElement

method and fills with JSON array

optionArray = [
    "daily",
    "weekly",
    "biweekly",
    "monthly"
];

// Creates <select> element
let selector = document.createElement('select');

for(let option in optionArray) {
    let value = optionArray[option];
  
    // Creates <option> element for <select>
    let newOption = document.createElement("option"); 
    
    newOption.value = value;
    newOption.innerHTML = value;
  
    selector.options.add(newOption);
}
// Adds the <select> element into the document object
document.body.appendChild(selector);

XML documents form a tree structure that starts at

the root

An

XML tree

starts at a

root element

and branches from the root to

child elements

<root>
  <child>
    <subchild>.....</subchild>
  </child>
</root>

The terms

parent

,

child

, and

sibling

are used to describe the relationships between elements. ...

Parents

have children.

Children

have parents.

Siblings

are children on the same level (brothers and sisters). ... We can use any of the online XML tree viewer tools to see the document's tree structure, like this one:

https://www.xmlviewer.org/

Books

XML document to see on tree-viewer

<books>
  <book category="cooking">
    <title lang="en">The goals</title>
    <author>Giada De Laurentiis</author>
    <year>2007</year>
    <price>30.00</price>
  </book>
  <book category="children">
    <title lang="en">12 rules for life</title>
    <author>J K. Rowling</author>
    <year>2002</year>
    <price>29.99</price>
  </book>
  <book category="web">
    <title lang="en">The richest man in Babilon</title>
    <author>Erik T. Ray</author>
    <year>2001</year>
    <price>39.95</price>
  </book>
</books>

The example below parses an XML document

address.xml

into an XML DOM object. Then extracts

contact

information using

JavaScript

<!DOCTYPE html>
<html>
   <body>
      <h1>TutorialsPoint DOM example </h1>
      <div>
         <b>Name:</b> <span id = "name"></span><br>
         <b>Company:</b> <span id = "company"></span><br>
         <b>Phone:</b> <span id = "phone"></span>
      </div>
      <script>
         if (window.XMLHttpRequest)
         {// code for IE7+, Firefox, Chrome, Opera, Safari
            xmlhttp = new XMLHttpRequest();
         }
        //  else
        //  {// code for IE6, IE5
        //     xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
        //  }
         xmlhttp.open("GET","address.xml",false);
         xmlhttp.send();
         xmlDoc = xmlhttp.responseXML;

         document.getElementById("name").innerHTML = xmlDoc.getElementsByTagName("name")[0].childNodes[0].nodeValue;
         document.getElementById("company").innerHTML = xmlDoc.getElementsByTagName("company")[0].childNodes[0].nodeValue;
         document.getElementById("phone").innerHTML = xmlDoc.getElementsByTagName("phone")[0].childNodes[0].nodeValue;
      </script>
   </body>
</html>

address.xml

file content

<?xml version = "1.0"?>
<contact>
   <name>Tanmay Patil</name>
   <company>TutorialsPoint</company>
   <phone>(011) 123-4567</phone>
</contact>

View settings:

getsebool -a | grep httpd

Setting to enable to connect to FB to another server:

setsebool -P httpd_can_network_connect_db 1

update ubunto

sudo apt update

install nginx

sudo apt install nginx

ufw allow 'Nginx HTTP'

sudo ufw allow 'Nginx HTTP'

Ubuntu comes with a nice command called ‘mysqldump’. We are going to use the command as shown below to backup our database. Replace the username, database_name and backup_file_name wit the correct values. Also, enter your database password when prompted to do so:

mysqldump -u username -p database_name > backup_file_name.sql