JSON unable to accept json_encode() arrays

Question

I am sending a simple array from my PHP file,

//example.php
if(0){
    return json_encode(['status'=>false, 'message'=>'Please enter a username']);
}

and in my ajax.js I have everything working, including the XHR object, and event handlers. All is find, except this line.

 // ...
 var x = JSON.parse(xmlhttp.responseText);
 console.log(x); 
// ...

But, I am getting the following error.

SyntaxError: JSON.parse: unexpected end of data at line 1 column 1 of the JSON data

I don't understand this. All the code is correct. Before using JSON, I used to pass from values from PHP using echo 'ok' and just do if(xmlhttp.responseText) == 'ok and it worked fine, but not with json

You'll have to look at whatever response your PHP actually returned (leading/trailing garbage/HTML). And if(0){ probably doesn't help. — mario
– mario, Commented Feb 19, 2015 at 23:46
Nope, the PHP file is clean. I checked. There is nothing being sent except the array. — robue-a7119895
– robue-a7119895, Commented Feb 19, 2015 at 23:47
Can you post the full response of the PHP file? Get it from your browsers console. — Scopey
– Scopey, Commented Feb 19, 2015 at 23:48
@Scopey the error is the full response, though there are two empty string being displayed before and after the error. both double-quoted empty strings. — robue-a7119895
– robue-a7119895, Commented Feb 19, 2015 at 23:50
Try running trim() or filter out empty elements in your array. — Scott
– Scott, Commented Feb 19, 2015 at 23:50

willeM_ Van Onsem · Accepted Answer · 2015-02-20 00:18:05Z

1

Two problems:

you use return which does not print anything to the output wheras echo actually prints text. Try using:
if(0) will always fail, so you will never print anything. You should use if(1) as trivial test. It is possible that you're PHP code can fail, but in that case you better also return an JSON formatted error message.

Something like:

if(test) { //test means you can do the action
    //do action
    echo json_encode(['return' => 'ok','result' => 'foobar']);
} else {
    echo json_encode(['return' => 'error']);
}

answered Feb 20, 2015 at 0:18

willeM_ Van Onsem

482k33 gold badges483 silver badges624 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

robue-a7119895 Over a year ago

Yeah, it turns out I should have used echo. the (0) part was written here by mistake. But, one problem I have is that, echo outputs data to the browser before actually javascript can for example redirect the page. Any solutions to this problem?

willeM_ Van Onsem Over a year ago

What output? The fetched page? It's rather hard to debug this without any page source...

robue-a7119895 Over a year ago

I mean, for example, in the code you have given. if there is no error, I can see {return:ok, result:foobar} in the page, because the javascript can decode the json format and do some action, like page redirect. So, in the registration page, I have, people will see the serialized data no matter what, because echo just outputs it to the browser.

Collectives™ on Stack Overflow

JSON unable to accept json_encode() arrays

1 Answer 1

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related