Tutorials References Exercises Menu
Paid Courses

JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Statements JS Syntax JS Comments JS Variables JS Let JS Const JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Events JS Strings JS String Methods JS String Search JS String Templates JS Numbers JS Number Methods JS Arrays JS Array Methods JS Array Sort JS Array Iteration JS Array Const JS Dates JS Date Formats JS Date Get Methods JS Date Set Methods JS Math JS Random JS Booleans JS Comparisons JS Conditions JS Switch JS Loop For JS Loop For In JS Loop For Of JS Loop While JS Break JS Typeof JS Type Conversion JS Bitwise JS RegExp JS Errors JS Scope JS Hoisting JS Strict Mode JS this Keyword JS Arrow Function JS Classes JS JSON JS Debugging JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words

JS Versions

JS Versions JS 2009 (ES5) JS 2015 (ES6) JS 2016 JS 2017 JS 2018 JS IE / Edge JS History

JS Objects

Object Definitions Object Properties Object Methods Object Display Object Accessors Object Constructors Object Prototypes Object Reference Object Map() Object Set()

JS Functions

Function Definitions Function Parameters Function Invocation Function Call Function Apply Function Closures

JS Classes

Class Intro Class Inheritance Class Static

JS Async

JS Callbacks JS Asynchronous JS Promises JS Async/Await

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM Forms DOM CSS DOM Animations DOM Events DOM Event Listener DOM Navigation DOM Nodes DOM Collections DOM Node Lists

JS Browser BOM

JS Window JS Screen JS Location JS History JS Navigator JS Popup Alert JS Timing JS Cookies

JS Web APIs

Web API Intro Web Forms API Web History API Web Storage API Web Worker API Web Fetch API Web Geolocation API

JS AJAX

AJAX Intro AJAX XMLHttp AJAX Request AJAX Response AJAX XML File AJAX PHP AJAX ASP AJAX Database AJAX Applications AJAX Examples

JS JSON

JSON Intro JSON Syntax JSON vs XML JSON Data Types JSON Parse JSON Stringify JSON Objects JSON Arrays JSON Server JSON PHP JSON HTML JSON JSONP

JS vs jQuery

jQuery Selectors jQuery HTML jQuery CSS jQuery DOM

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser JS Editor JS Exercises JS Quiz JS Certificate

JS References

JavaScript Objects HTML DOM Objects


JSON PHP


A common use of JSON is to read data from a web server, and display the data in a web page.

This chapter will teach you how to exchange JSON data between the client and a PHP server.


The PHP File

PHP has some built-in functions to handle JSON.

Objects in PHP can be converted into JSON by using the PHP function json_encode():

PHP file

<?php
$myObj->name = "John";
$myObj->age = 30;
$myObj->city = "New York";

$myJSON = json_encode($myObj);

echo $myJSON;
?>
Show PHP file »

The Client JavaScript

Here is a JavaScript on the client, using an AJAX call to request the PHP file from the example above:

Example

Use JSON.parse() to convert the result into a JavaScript object:

const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  document.getElementById("demo").innerHTML = myObj.name;
}
xmlhttp.open("GET", "demo_file.php");
xmlhttp.send();
Try it Yourself »


PHP Array

Arrays in PHP will also be converted into JSON when using the PHP function json_encode():

PHP file

<?php
$myArr = array("John", "Mary", "Peter", "Sally");

$myJSON = json_encode($myArr);

echo $myJSON;
?>
Show PHP file »

The Client JavaScript

Here is a JavaScript on the client, using an AJAX call to request the PHP file from the array example above:

Example

Use JSON.parse() to convert the result into a JavaScript array:

var xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  document.getElementById("demo").innerHTML = myObj[2];
}
xmlhttp.open("GET", "demo_file_array.php", true);
xmlhttp.send();
Try it Yourself »

PHP Database

PHP is a server side programming language, and can be used to access a database.

Imagine you have a database on your server, and you want to send a request to it from the client where you ask for the 10 first rows in a table called "customers".

On the client, make a JSON object that describes the numbers of rows you want to return.

Before you send the request to the server, convert the JSON object into a string and send it as a parameter to the url of the PHP page:

Example

Use JSON.stringify() to convert the JavaScript object into JSON:

const limit = {"limit":10};
const dbParam = JSON.stringify(limit);
xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  document.getElementById("demo").innerHTML = this.responseText;
}
xmlhttp.open("GET","json_demo_db.php?x=" + dbParam);
xmlhttp.send();
Try it Yourself »

Example explained:

  • Define an object containing a "limit" property and value.
  • Convert the object into a JSON string.
  • Send a request to the PHP file, with the JSON string as a parameter.
  • Wait until the request returns with the result (as JSON)
  • Display the result received from the PHP file.

Take a look at the PHP file:

PHP file

<?php
header("Content-Type: application/json; charset=UTF-8");
$obj = json_decode($_GET["x"], false);

$conn = new mysqli("myServer", "myUser", "myPassword", "Northwind");
$stmt = $conn->prepare("SELECT name FROM customers LIMIT ?");
$stmt->bind_param("s", $obj->limit);
$stmt->execute();
$result = $stmt->get_result();
$outp = $result->fetch_all(MYSQLI_ASSOC);

echo json_encode($outp);
?>

PHP File explained:

  • Convert the request into an object, using the PHP function json_decode().
  • Access the database, and fill an array with the requested data.
  • Add the array to an object, and return the object as JSON using the json_encode() function.

Use the Data

Example

xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  let text = "";
  for (let x in myObj) {
    text += myObj[x].name + "<br>";
  }
  document.getElementById("demo").innerHTML = text;
}
Try it Yourself »

PHP Method = POST

When sending data to the server, it is often best to use the HTTP POST method.

To send AJAX requests using the POST method, specify the method, and the correct header.

The data sent to the server must now be an argument to the send() method:

Example

const dbParam = JSON.stringify({"limit":10});
const xmlhttp = new XMLHttpRequest();
xmlhttp.onload = function() {
  const myObj = JSON.parse(this.responseText);
  let text ="";
  for (let x in myObj) {
    text += myObj[x].name + "<br>";
  }
  document.getElementById("demo").innerHTML = text;
}
xmlhttp.open("POST", "json_demo_db_post.php");
xmlhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xmlhttp.send("x=" + dbParam);
Try it Yourself »

The only difference in the PHP file is the method for getting the transferred data.

PHP file

Use $_POST instead of $_GET:

<?php
header("Content-Type: application/json; charset=UTF-8");
$obj = json_decode($_POST["x"], false);

$conn = new mysqli("myServer", "myUser", "myPassword", "Northwind");
$stmt = $conn->prepare("SELECT name FROM customers LIMIT ?");
$stmt->bind_param("s", $obj->limit);
$stmt->execute();
$result = $stmt->get_result();
$outp = $result->fetch_all(MYSQLI_ASSOC);

echo json_encode($outp);
?>