THE WORLD'S LARGEST WEB DEVELOPER SITE
×

JS Tutorial

JS HOME JS Introduction JS Where To JS Output JS Syntax JS Statements JS Comments JS Variables JS Operators JS Arithmetic JS Assignment JS Data Types JS Functions JS Objects JS Scope JS Events JS Strings JS String Methods JS Numbers JS Number Methods JS Math JS Random JS Dates JS Date Formats JS Date Methods JS Arrays JS Array Methods JS Array Sort JS Booleans JS Comparisons JS Conditions JS Switch JS Loop For JS Loop While JS Break JS Type Conversion JS Bitwise JS RegExp JS Errors JS Debugging JS Hoisting JS Strict Mode JS Style Guide JS Best Practices JS Mistakes JS Performance JS Reserved Words JS Versions JS JSON

JS Forms

JS Forms Forms API

JS Objects

Object Definitions Object Properties Object Methods Object Prototypes

JS Functions

Function Definitions Function Parameters Function Invocation Function Closures

JS HTML DOM

DOM Intro DOM Methods DOM Document DOM Elements DOM HTML DOM CSS DOM Animations DOM Events DOM EventListener DOM Navigation DOM Nodes DOM Nodelist

JS Browser BOM

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

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 Objects JSON Arrays JSON Parse JSON Stringify JSON PHP JSON HTML JSON JSONP

JS Examples

JS Examples JS HTML DOM JS HTML Input JS HTML Objects JS HTML Events JS Browser 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:

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();
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.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        var 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 should be used for operations that can only be performed by a server, like accessing a database.

Imagine you have a database on the server, containing customers, products, and suppliers.

You want to make a request to the server where you ask for the 10 first records in the "customers" table:

Example

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

obj = { "table":"customers", "limit":10 };
dbParam = JSON.stringify(obj);
xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        document.getElementById("demo").innerHTML = this.responseText;
    }
};
xmlhttp.open("GET", "json_demo_db.php?x=" + dbParam, true);
xmlhttp.send();
Try it Yourself »

Example explained:

  • Define an object containing a table property and a limit property.
  • 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");
$result = $conn->query("SELECT name FROM ".$obj->$table." LIMIT ".$obj->$limit);
$outp = array();
$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.

Loop Through the Result

Convert the result received from the PHP file into a JavaScript object, or in this case, a JavaScript array:

Example

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

...
xmlhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        myObj = JSON.parse(this.responseText);
        for (x in myObj) {
            txt += myObj[x].name + "<br>";
        }
        document.getElementById("demo").innerHTML = txt;
    }
};
...
Try it Yourself »

PHP Method = POST

When sending data to the server, it is often be 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

obj = { "table":"customers", "limit":10 };
dbParam = JSON.stringify(obj);
xmlhttp = new XMLHttpRequest();
xmlhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
        myObj = JSON.parse(this.responseText);
        for (x in myObj) {
            txt += myObj[x].name + "<br>";
        }
        document.getElementById("demo").innerHTML = txt;
    }
};
xmlhttp.open("POST", "json_demo_db_post.php", true);
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");
$result = $conn->query("SELECT name FROM ".$obj->$table." LIMIT ".$obj->$limit);
$outp = array();
$outp = $result->fetch_all(MYSQLI_ASSOC);

echo json_encode($outp);
?>