Can't parse XMLHttpRequest.response to Object or Array

Question

I'm trying to refresh the content of my cells of an table. Therefore, I have a JavaScript which contains an AJAX request to a .php file, which creates my content that I want to insert into my table via JavaScript. The .php files last command is something like echo json_encode($result);.

Back in the JavaScript it says:

var testarray = xmlhttp.response;
alert(testarray);

But the outut from the alert looks like:

{"1":{"1":"3","2":"0","3":"2","4":"0"}}{"1":{"1":"3","2":"0","3":"2","4":"0"},"2":{"1":"2","2":"1","3":"1","4":"1"}}...

So it seems the variable testarray isn't handled as an array but as a string. I already tried var testarray = JSON.parse(xmlhttp.response), but this doesn’t work. Neither does eval() works.

I don't know what to do, so the response of my request becomes an object.

You encode your results as json, so you get json. You can get arrays, but why would you. JSON is awesome. See this "json to array" thread stackoverflow.com/questions/6872832/json-to-javascript-array — Gerben Jacobs
– Gerben Jacobs, Commented Aug 27, 2013 at 8:42
@oli Make sure you're JSON-encoding a real array on the server side. — Dziad Borowy
– Dziad Borowy, Commented Aug 27, 2013 at 8:58
@Gerben Jacobs my variable build out of the response don't have to be an array. But I'm looking for a way to have access to the single elements of my array I've createt inside my php file. If this works anyhow without forcing my response to be an Array this would be fine, too — oli
– oli, Commented Aug 27, 2013 at 9:01

pdem · Accepted Answer · 2013-08-27 09:31:25Z

1

There are 2 strange things in your json:

this part is not json valid: ...}{... two object should be separated by comas
The notation is object with string indexes not array with int indexes it should be something like: [[1,2,3,4],[5,6,7,8]]

for the point 1. it looks like you have a loop that concatenate many json

for the point 2. the object notation can be used as an array so it doesn't matter

Some code:

    //the folowing code doesn't work: }{ is not parsable
var a=JSON.parse('{"1":{"1":"3","2":"0","3":"2","4":"0"}}{"1":{"1":"3","2":"0","3":"2","4":"0"},"2":{"1":"2","2":"1","3":"1","4":"1"}}');

    //the folowing code work and the object can be used as an array
var a=JSON.parse('{"1":{"1":"3","2":"0","3":"2","4":"0"},"2":{"1":"2","2":"1","3":"1","4":"1"}}');
alert(JSON.stringify(a[1]));


    //the folowing code displays the real notation of a javascript array:
alert(JSON.stringify([1,2,3,4]));

answered Aug 27, 2013 at 9:31

pdem

4,1001 gold badge27 silver badges41 bronze badges

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

1 Comment

oli Over a year ago

Many thanks to your answer. You are right.In the php file, I didn't echo'd my $result array at the end, but inside of a for loop. I changed this and now it works.

Dziad Borowy · Accepted Answer · 2013-08-27 09:35:44Z

0

I think that the problem here might be that your arrays do not have index 0.

e.g. if you output this from the server - it would produce an object:

$result = [];
for ($i = 1; $i < 5; $i++) $result[$i] = $i;
echo json_encode($result);      // outputs an object

if you output this from the server - it would produce an array:

$result = [];
for ($i = 0; $i < 5; $i++) $result[$i] = $i;
echo json_encode($result);     // produces an array

Anyways, even if your server outputs array as object - you should still be able to access it normally in javascript:

var resp = xmlhttp.responseText,  // "responseText" - if you're using native js XHR
    arr = JSON.parse(resp);       // should give you an object
console.log(arr[1]);              // should give you the first element of that object

edited Aug 27, 2013 at 9:35

answered Aug 27, 2013 at 9:09

Dziad Borowy

12.6k4 gold badges44 silver badges54 bronze badges

Collectives™ on Stack Overflow

Can't parse XMLHttpRequest.response to Object or Array

2 Answers 2

1 Comment

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related