Simple jQuery, PHP and JSONP example?

Question

I am facing the same-origin policy problem, and by researching the subject, I found that the best way for my particular project would be to use JSONP to do cross-origin requests.

I've been reading this article from IBM about JSONP, however I am not 100% clear on what is going on.

All I am asking for here, is a simple jQuery>PHP JSONP request (or whatever the terminology may be ;) ) - something like this (obviously it is incorrect, its just so you can get an idea of what I am trying to achieve :) ):

jQuery:

$.post('http://MySite.com/MyHandler.php',{firstname:'Jeff'},function(res){
    alert('Your name is '+res);
});

PHP:

<?php
  $fname = $_POST['firstname'];
  if($fname=='Jeff')
  {
    echo 'Jeff Hansen';
  }
?>

How would I go about converting this into a proper JSONP request? And if I were to store HTML in the result to be returned, would that work too?

Solution 1

When you use $.getJSON on an external domain it automatically actions a JSONP request, for example my tweet slider here

If you look at the source code you can see that I am calling the Twitter API using .getJSON.

So your example would be: THIS IS TESTED AND WORKS (You can go to http://smallcoders.com/javascriptdevenvironment.html to see it in action)

//JAVASCRIPT

$.getJSON('http://www.write-about-property.com/jsonp.php?callback=?','firstname=Jeff',function(res){
    alert('Your name is '+res.fullname);
});

//SERVER SIDE
  <?php
 $fname = $_GET['firstname'];
      if($fname=='Jeff')
      {
          //header("Content-Type: application/json");
         echo $_GET['callback'] . '(' . "{'fullname' : 'Jeff Hansen'}" . ')';

      }
?>

Note the ?callback=? and +res.fullname

Solution 2

First of all you can't make a POST request using JSONP.

What basically is happening is that dynamically a script tag is inserted to load your data. Therefore only GET requests are possible.

Furthermore your data has to be wrapped in a callback function which is called after the request is finished to load the data in a variable.

This whole process is automated by jQuery for you. Just using $.getJSON on an external domain doesn't always work though. I can tell out of personal experience.

The best thing to do is adding &callback=? to you url.

At the server side you've got to make sure that your data is wrapped in this callback function.

ie.

echo $_GET['callback'] . '(' . $data . ')';

EDIT:

Don't have enough rep yet to comment on Liam's answer so therefore the solution over here.

Replace Liam's line

 echo "{'fullname' : 'Jeff Hansen'}";

with

 echo $_GET['callback'] . '(' . "{'fullname' : 'Jeff Hansen'}" . ')';

Solution 3

More Suggestion

JavaScript:

$.ajax({
        url: "http://FullUrl",
        dataType: 'jsonp',
        success: function (data) {

            //Data from the server in the in the variable "data"
            //In the form of an array

        }

});

PHP CallBack:

<?php

$array = array(
     '0' => array('fullName' => 'Meni Samet', 'fullAdress' => 'New York, NY'),
     '1' => array('fullName' => 'Test 2', 'fullAdress' => 'Paris'),
);

if(isset ($_GET['callback']))
{
    header("Content-Type: application/json");

    echo $_GET['callback']."(".json_encode($array).")";

}
?>

Solution 4

To make the server respond with a valid JSONP array, wrap the JSON in brackets () and preprend the callback:

echo $_GET['callback']."([{'fullname' : 'Jeff Hansen'}])";

Using json_encode() will convert a native PHP array into JSON:

$array = array(
    'fullname' => 'Jeff Hansen',
    'address' => 'somewhere no.3'
);
echo $_GET['callback']."(".json_encode($array).")";

Solution 5

Simple jQuery, PHP and JSONP example is below:

window.onload = function(){
	$.ajax({
		cache: false,
		url: "https://jsonplaceholder.typicode.com/users/2",
		dataType: 'jsonp',
		type: 'GET',
		success: function(data){
			console.log('data', data)
		},
		error: function(data){
			console.log(data);
		}
	});
};

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

View more solutions

Comments

[Jeff]

And what about the server-sided part of the story? :)

[Jeff]

So no need to do res.fullname? :)

[Jeff]

I am choking on the last part - why are you doing the '('.$data...?

[Liam Bailey]

I spotted that after your first comment amended

[Ewout Kleinsmann]

As I said your data has to be wrapped into a Javascript function. Liam's example won't work. The actual response should look like this: callbackFunction({"fullname": "Jeff Hansen"})

[Liam Bailey]

Sorry, but you are wrong, yes you need the ?callback= on the url, but if you just make it ?callback=? you can send your data in JSON in the second parameter. I know because I have done it.

[Ewout Kleinsmann]

You can send it, but you can't receive it without adding the wrapper callback function. EDIT: You're talking about the client-side in jQuery, but I'm talking about the server-side in PHP which needs adjusting.

[Jeff]

Firebug reports "invalid label: {'firstname':'Jeff'}", and uuhm.. Its not working, nothing is happening

[Jeff]

@Ewout - I adjusted my PHP code, but it did not return either. Are you sure its parantheses and not curly brackets?

[Jeff]

@Ewout - Yup, did before I saw your edit tho, but I read your "callbackFunction({...." :)

[Jeff]

The hard part is now to decide which one of you get the mark! You both contributed equally IMO.

[Jeff]

@Ewout - I was not getting any error, nothing happend - however it is fixed now :)

[Ewout Kleinsmann]

I edited Liam's answer. Once the edit is peer reviewed you can accept that answer, as it will be a complete example for future references.

[Liam Bailey]

We were both right, the second parameter needs changing in the getJSON call as well. I have tested it and got it working and posted working code

[Liam Bailey]

@Jeff I went away and set up a cross server request on two of my sites, the code above works perfectly.

[Ewout Kleinsmann]

@Liam: an object as second parameter for a getJSON call should actually be perfectly fine. Are you sure your code is working? I find that hard to believe since you're using curly brackets instead of parantheses to wrap your callback function.

[Liam Bailey]

Yes, it works I tried with parens, it didn't work, then changed to curly brackets and it works like a dream. Yes object is fine for second param too, but not how I originally had it.

[Jeff]

Looks like you wrapped more curly brackets around? :)

[Jeff]

Looks like the 3rd answer uses square brackets - could it be all bracket types are valid?

[Liam Bailey]

You can go to smallcoders.com/javascriptdevenvironment.html to see it in action

[Ewout Kleinsmann]

Actually it can't be. Only parantheses should work since the callback function is a Javascript function which has to be called. @Liam could you show me your working example with curly brackets? I'm quite curious how that's working... EDIT: I see your example, but you are using parantheses and no curly brackets...

[Ewout Kleinsmann]

In your answer you've got echo $_GET['callback'] . '{' . "{'fullname' : 'Jeff Hansen'}" . '}'; But your response is indicating that you're using echo $_GET['callback'] . '(' . "{'fullname' : 'Jeff Hansen'}" . ')';

[Ewout Kleinsmann]

Wow, didn't mean to upset you. This is the response of your jsonp.php: jQuery162012322438252158463_1311540946688({'fullname' : 'Jeff Hansen'}). The code you provided in your answer won't produce this. It would produce this: jQuery162012322438252158463_1311540946688{{'fullname' : 'Jeff Hansen'}}

[Liam Bailey]

You are right, I apologise. I had changed the code to curly braces but had not added the file to the server. Parenthesis works, curly braces doesn't. Answer updated.

[Alastair]

The question was regarding JSONP which requires the server's response to be wrapped with the client-callback and brackets e.g. callback123([{a:1}])

[djfried]

never echo a user provided parameter without sanitizing!

[Guicara]

Server side, you should returns header("Content-Type: application/javascript"); to avoid MIME TYPES errors.

[moreirapontocom]

Awesome!! Thank you.