JavaScript: Encounter issues while parsing JSON due to encountering an unexpected token error

Question

JavaScript: Encounter issues while parsing JSON due to encountering an unexpected token error

I was able to successfully parse a JSON URL using Java code in the past, but now I need to migrate it to JavaScript. However, when attempting to parse the JSON using JavaScript, I encountered a syntax error: Unexpected token i.

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

Below is my JavaScript code:

//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 is shown below and can parse the same URL correctly without any errors:

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 from parsing the JSON data should look like this:

{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_:''},

javascript java json

Answer 1

Answer №1

It appears that the source data does not contain valid JSON information. As noted on http://json.org/, keys in JSON must be wrapped in double quotes and this also applies to string values:

{ "identifier": "ID" }

The error message indicates that the parser was anticipating a double quote instead of the 'i' character.

I recommend testing your code with a small snippet to confirm it can handle valid JSON properly.

Answer 2

It appears that the source data does not contain valid JSON information. As noted on http://json.org/, keys in JSON must be wrapped in double quotes and this also applies to string values:

{ "identifier": "ID" }

The error message indicates that the parser was anticipating a double quote instead of the 'i' character.

I recommend testing your code with a small snippet to confirm it can handle valid JSON properly.

Answer 3

Answer №2

To handle your JSON data that is not in strict mode, consider using eval instead. In a strict mode JSON data, the keys must be double-quoted.

Examples

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

function test(jsonData, parser){
  try{
    console.log("Parsing with "+parser.name+" => "+JSON.stringify(parser("("+jsonData+")")));
  }catch(e){
    console.log('Cannot parse with '+parser.name);
  }
}
test(jsonData, JSON.parse);
test(jsonData, eval);

Strict Mode Support in JSON.parse Only

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));

Enhancing Security by Encapsulating eval()

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!");
    }
});

Answer 4

To handle your JSON data that is not in strict mode, consider using eval instead. In a strict mode JSON data, the keys must be double-quoted.

Examples

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

function test(jsonData, parser){
  try{
    console.log("Parsing with "+parser.name+" => "+JSON.stringify(parser("("+jsonData+")")));
  }catch(e){
    console.log('Cannot parse with '+parser.name);
  }
}
test(jsonData, JSON.parse);
test(jsonData, eval);

Strict Mode Support in JSON.parse Only

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));

Enhancing Security by Encapsulating eval()

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!");
    }
});

JavaScript: Encounter issues while parsing JSON due to encountering an unexpected token error

Answer №1

Answer №2

Examples

Strict Mode Support in JSON.parse Only

Enhancing Security by Encapsulating eval()

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