JavaScript: Unable to parse json with error unexpected token

Question

I manage to parse a json url with java code previously but need to migrate it to javascript now. When I parse using JavaScript, syntaxerror: Unexpected token I occurred

SyntaxError: Unexpected token i in JSON at position 2
at JSON.parse (<anonymous>)
at success (homeCtrl.js:1060)
at processQueue (ionic.bundle.js:29127)
at ionic.bundle.js:29143
at Scope.$eval (ionic.bundle.js:30395)
at Scope.$digest (ionic.bundle.js:30211)
at Scope.$apply (ionic.bundle.js:30503)
at done (ionic.bundle.js:24824)
at completeRequest (ionic.bundle.js:25022)
at XMLHttpRequest.requestLoaded (ionic.bundle.js:24963)
(anonymous) @ ionic.bundle.js:26794
(anonymous) @ ionic.bundle.js:23507
processQueue @ ionic.bundle.js:29135
(anonymous) @ ionic.bundle.js:29143
$eval @ ionic.bundle.js:30395
$digest @ ionic.bundle.js:30211
$apply @ ionic.bundle.js:30503
done @ ionic.bundle.js:24824
completeRequest @ ionic.bundle.js:25022
requestLoaded @ ionic.bundle.js:24963

My javascript is as below:

//scrap singapore
function topVolumeGainerLosersSingapore(type) {
$ionicLoading.show();

var url = "http://www.sgx.com/JsonRead/JsonData?qryId=RStock&timeout=30";

$http({
method: 'GET',
url: url,
transformResponse: undefined,
headers: {
"Content-Type":"text/plain",
"Accept":"text/plain"
}
}).then(function success(response) {
// this function will be called when the request is success
var text = response.data;
//console.log(text);
var replaceData = text.substring(text.indexOf("&&")+2);
//console.log(replaceData);
var newData = JSON.parse(replaceData);
console.log(newData);

}, function error(response) {
// this function will be called when the request returned error status
$ionicLoading.hide();
console.log(response);
});
}

The java code can parse correctly with no error for the same url

public class MainActivity extends AppCompatActivity {

    private static final String TAG = MainActivity.class.getSimpleName();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new AsyncTas().execute();
    }

    private class AsyncTas extends AsyncTask<Void,Void,Void>{

        @Override
        protected Void doInBackground(Void... voids) {
            HttpURLConnection urlConnection = null;
            String urlString = "http://www.sgx.com/JsonRead/JsonData?qryId=RStock&timeout=30";
            try {
                urlConnection = (HttpURLConnection) new URL(urlString).openConnection();
                //String result = readIt(new BufferedInputStream(urlConnection.getInputStream()));
                BufferedReader bufferedReader = new BufferedReader(
                        new InputStreamReader(urlConnection.getInputStream()));

                // Grab the results
                StringBuilder log = new StringBuilder();
                String line;
                while ((line = bufferedReader.readLine()) != null) {
                    log.append(line + "\n");
                }
                String result = log.toString();

                result = result.substring(result.indexOf("&&") + 2);
                JSONObject jo = new JSONObject(result);

                Log.e(TAG, "doInBackground: "+result);
            } catch (IOException e) {
                e.printStackTrace();
            } catch (JSONException e) {
                e.printStackTrace();
                Toast.makeText(getApplicationContext(),"Unable to parse json "+e.getMessage(),Toast.LENGTH_LONG).show();
            }
            return null;
        }
    }
}

The desired output is as below:

{identifier:'ID', label:'As at 08-03-2017 2:48 PM',items:[{ID:0,N:'3Cnergy',SIP:'',NC:'502',R:'',I:'',M:'t',LT:0.000,C:0.000,VL:0.000,BV:100.000,B:'0.042',S:'0.047',SV:70.000,O:0.000,H:0.000,L:0.000,V:0.000,SC:'2',PV:0.040,PTD:'20170307',BL:'100',EX:'',EJ:'',CLO:'',P:0.0,P_:'X',V_:''},{ID:1,N:'800 Super',SIP:'',NC:'5TG',R:'',I:'',M:'t',LT:1.160,C:-0.020,VL:51.400,BV:10.500,B:'1.160',S:'1.170',SV:10.000,O:1.180,H:1.180,L:1.160,V:60324.500,SC:'A',PV:1.180,PTD:'20170307',BL:'100',EX:'',EJ:'',CLO:'',P:-1.694915234375,P_:'X',V_:''},{ID:2,N:'8Telecom',SIP:'',NC:'AZG',R:'',I:'',M:'',LT:0.000,C:0.000,VL:0.000,BV:5.000,B:'0.130',S:'0.140',SV:10.000,O:0.000,H:0.000,L:0.000,V:0.000,SC:'2',PV:0.135,PTD:'20170306',BL:'100',EX:'',EJ:'',CLO:'',P:0.0,P_:'X',V_:''},{ID:3,N:'A-Smart',SIP:'',NC:'BQC',R:'',I:'',M:'',LT:0.570,C:-0.020,VL:60.000,BV:31.000,B:'0.570',S:'0.580',SV:10.000,O:0.575,H:0.575,L:0.570,V:34350.000,SC:'2',PV:0.590,PTD:'20170307',BL:'100',EX:'',EJ:'',CLO:'',P:-3.38983046875,P_:'X',V_:''},

Albert-Jan Verhees · Answer 1 · 2017-03-08 08:10:30Z

up vote 3 down vote

It seems like the source data doesn't contain valid JSON data. According to http://json.org/ a key is a String and therefore must be wrapped in double quotes, which also applies to the String values:

{ "identifier": "ID" }

As your error states, the parser was expecting a double quote, rather then the i character.

I suggest you test your code with a small snippet first to verify it works with valid JSON data.

answered 18 hours ago

Albert-Jan Verhees

785816

but it works in java, why? – bkcollection 18 hours ago

1

Because Java does not expect strict mode JSON: developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… – Björn M 18 hours ago

Thats the difference between JSON.parse and eval(). The first one expects strict JSON and the other one JavaScript. You source data is written in the last format. See w3schools.com/js/js_json_syntax.asp – Albert-Jan Verhees 18 hours ago

@BjörnM, any workaround that you can suggested? Thanks – bkcollection 18 hours ago

I think @holi-java has provided that in his answer – Albert-Jan Verhees 18 hours ago

| show 1 more comment

holi-java · Answer 2 · 2017-03-08 09:49:16Z

use eval instead.your json data is not a strict mode.a strict mode json data the key must be double-quoted.

Demos

var json="{} && { identifier: 'ID' }";

function test(json,parser){
  try{
  console.log("parsing by "+parser.name+" => "+JSON.stringify(parser("("+json+")")));
  }catch(e){
    console.log('Can not parsed by '+parser.name);
  }
}
test(json,JSON.parse);
test(json,eval);

JSON.parse only supported strict mode

var formats={
 strict:'{"foo":"bar"}',
 'single-quotes':"{'foo':'bar'}",
 'no-quotes':"{foo:'bar'}"
};

function test(parser){
  return parser.name+" supports " +Object.keys(formats).reduce(function(supports,format){
    try{
       parser(formats[format]);
       supports.push(format);
    }catch(e){      
    }finally{return supports;}
  },[]);
}
function parseJSON(json){
 return eval("("+json+")");
}
console.log(test(parseJSON));
console.log(test(JSON.parse));

Encapsulate eval() solve the security problem.

window.$ = window.jQuery = {};
function foo() {
    return 'bar';
}

parse = (function () {
    //disable all global keys
    eval("var " + Object.keys(window).join(', '));

    return function (_) {
        return eval("(" + _ + ")");
    };
})();


var snippets = [
    "window",
    "location",
    "$",
    "jQuery",
    "location.href='http://www.example.com'",
    'local',
    "{foo:'bar'}",
    "foo()",
    "eval('window')",
    'function ref(){return window}()'
];
snippets.forEach(function (snippet) {
    var local = 'local value';
    var expression = "parse(" + JSON.stringify(snippet) + ")";
    try {
        console.log(expression + " => " + JSON.stringify(parse(snippet)));
    } catch (e) {
        console.error(expression + " failed!");
    }
});

Eval() should not be used for JSON parsing both for security and efficiency reasons. developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/…! — Björn M, 18 hours ago
@BjörnM eval has security problem,but you can encapsulate it to disallowed access others only global variables can access. — holi-java, 18 hours ago
In my opinion simply fixing the input is more sustenaible than a complicated legacy solution. As I understand it the questioner is creating the JSON, so it it possible to fix it before the baby falls into the well instead of getting it out afterwards. If there is no way out your solution solves legacy parsing. — Björn M, 13 hours ago

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JavaScript: Unable to parse json with error unexpected token

2 Answers 2

Demos

JSON.parse only supported strict mode

Encapsulate eval() solve the security problem.

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JavaScript: Unable to parse json with error unexpected token

2 Answers 2

Demos

JSON.parse only supported strict mode

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