How to get JSON to successfully parse a XMLHttpRequest string?

Question

I'm using the Goo.gl URL shortener to shorten links. I sed it a Json string and it return results like this which gets stored in xmlHttp.response:

"{
 "kind": "urlshortener#url",
 "id": "http://goo.gl/mR2d",
 "longUrl": "http://google.com/"
}"

After sending the code, I try to parse it using JSON:

 xmlHttp.send(jsonStr);
 var short_url = JSON.parse(xmlHttp.response).id ;

When this code runs in a function, I get the following "Unexpected end of input" error:

getShortURL("http://google.com");
SyntaxError: Unexpected end of input
arguments: Array[0]
get message: function () { [native code] }
get stack: function () { [native code] }
set message: function () { [native code] }
set stack: function () { [native code] }
type: "unexpected_eos"
__proto__: Error

I had thought there may be some issue with the quotes in the string. What would be a good way to fix the problem?

you mean :var short_url = JSON.parse(xmlHttp.response.id) ; does eval() work? — Sajjan Sarkar, Nov 05 '12 at 21:42
There are not really quotes around the JSON, are they? Please post an actual response, I can't believe it's invalid JSON — Bergi, Nov 05 '12 at 21:42
You can not do this with plain JavaScript since calling google's service requires a post and they do not support JSONP. — epascarello, Nov 05 '12 at 21:45
Can you trim the beginning and ending quotes before parsing the JSON? — Joshua Dwire, Nov 05 '12 at 21:47
@Bergi, maybe that's just how Chrome's console displays it, and there's another reason for the error. — Ari, Nov 05 '12 at 21:52
Yeah, that's how console.log does it in the most browsers - they show quotes around to indicate it's a string, but don't escape the contents - they just print it as is, including linebreaks etc. That means your JSON is actually valid, could you please show us the entire error message? — Bergi, Nov 05 '12 at 21:57
OK, I edited the question. It actually seems I can get something to work in the console when doing it one line at a time, but not when running a whole function. — Ari, Nov 05 '12 at 22:05
Please print the stack trace and the whole message, not only the error object serialisation which only tells us there were getters for those... — Bergi, Nov 05 '12 at 22:19
The most simple case works for me using JSONP. I'm not getting any errors: http://jsfiddle.net/mZTPn/. — pimvdb, Nov 05 '12 at 22:22

score 1 · Accepted Answer · answered Nov 06 '12 at 01:39

I think I realized what was wrong. The code tries to get the information from the XMLHttpRequest before it actually has anything. Need to wait until xmlHttp.onreadystatechange and xmlHttp.readyState == 4 and then get out the shortened URL. Then can send it where needed.

(Wasn't used to these kind of asynchronous issues...)

score 0 · Answer 2 · edited May 23 '17 at 12:27

0

See JSON: why are forward slashes escaped?

My guess is that maybe the JSON parser you're using is expecting forward slashes to be escaped. See if this input is accepted instead:

{
    "kind": "urlshortener#url",
    "id": "http:\/\/goo.gl\/mR2d",
    "longUrl": "http:\/\/google.com\/"
}

edited May 23 '17 at 12:27

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answered Nov 05 '12 at 22:23

Jacob

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How to get JSON to successfully parse a XMLHttpRequest string?

2 Answers2