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Error when converting eval() to JSON.parse()

I have a snippet code with eval() as shown below:
var data = "{listUpdated:[],listConflictOrMerge:[]}"; //returned from Ajax
var results = eval("(" + data + ")");
console.log(results)
As you can see, the data is my input value returned from ajax request. When using eval(), it can be parsed to 2 array objects.
And now I don't want to use eval() anymore, so I try using JSON.parse(). However, there is an error.
var data = "{listUpdated:[],listConflictOrMerge:[]}"; //returned from Ajax
var results = JSON.parse(data);
console.log(results)
my purpose is that I don't want to use eval() to parse data anymore.
So, is there any ways can do that?.
I try using JSON, but I got unlucky. Am I wrong somewhere?

The data you're trying to parse isn't valid JSON, so JSON.parse can't parse it.
Keys in JSON objects must be quoted, just like any other string. The form you're using is valid in Javascript, but invalid in JSON.

var data = '{"listUpdated":[],"listConflictOrMerge":[]}';
var results =JSON.parse(data);
console.log(results)

Parse JSON Data from a String variable and convert it to objects in a $scope.variable

I have a string variable containg JSON data as below.
var jsonstring = [{"latitude":"51.5263","longitude":"-0.120285","altitude":"","device":"123","rating":"5","region":"Europe","customer":"","time":"1-2 Weeks","error":"Error 1","application":"Phone","age":"< 1 Year"},
{"latitude":"27.58","longitude":"23.43","altitude":"","device":"Asc 140","rating":"4","region":"Africa","customer":"","time":"< 1 Week","error":"Error 1","application":"PCB","age":"1-3 Years"},
{"latitude":"39.55","longitude":"116.25","altitude":"","device":"CVB","rating":"4","region":"China","customer":"","time":"1-2 Weeks","error":"Error 2","application":"Sorting","age":"3-5 Years"}]
I want to get this string and convert it to an array of objects (which would be a $scope.variable) so that i can be able to access each object individually.
I tried to use the JSON.parse() but it gets the entire string into one object instead of multiple objects.
Kindly help me with this.

You've to parse the entire string with JSON.parse.
Each object in the array can then be reached like any other array, e.g. myArray[index], myArray.map() / myArray.forEach() etc

[{"latitude":"51.5263","longitude":"-0.120285","altitude":"","device":"123","rating":"5","region":"Europe","customer":"","time":"1-2 Weeks","error":"Error 1","application":"Phone","age":"< 1 Year"},
{"latitude":"27.58","longitude":"23.43","altitude":"","device":"Asc 140","rating":"4","region":"Africa","customer":"","time":"< 1 Week","error":"Error 1","application":"PCB","age":"1-3 Years"},
{"latitude":"39.55","longitude":"116.25","altitude":"","device":"CVB","rating":"4","region":"China","customer":"","time":"1-2 Weeks","error":"Error 2","application":"Sorting","age":"3-5 Years"}]
This is an array object.It's not a string object.
You can try again like this:
var jsonString = "[]";
var json = JSON.parse(jsonString);

var jsonstring = '[{"latitude":"51.5263","longitude":"-0.120285","altitude":"","device":"123","rating":"5","region":"Europe","customer":"","time":"1-2 Weeks","error":"Error 1","application":"Phone","age":"< 1 Year"}, {"latitude":"27.58","longitude":"23.43","altitude":"","device":"Asc 140","rating":"4","region":"Africa","customer":"","time":"< 1 Week","error":"Error 1","application":"PCB","age":"1-3 Years"}, {"latitude":"39.55","longitude":"116.25","altitude":"","device":"CVB","rating":"4","region":"China","customer":"","time":"1-2 Weeks","error":"Error 2","application":"Sorting","age":"3-5 Years"}]';
$scope.variable = JSON.parse(jsonstring);

The JSON.parse() method parses a string as JSON.
Code in your question, shows that you are trying to parse a JS object and not a string.
In the following example, you get an error if you try to parse a JS object.
var jsonstring = [{},{}];
JSON.parse(jsonstring); // ERROR Uncaught SyntaxError: Unexpected token o
The following works instead (please note jsonstring is a string and not an object here):
var jsonstring = '[{},{}]';
JSON.parse(jsonstring); // OK

How can I properly use the javascript function JSON.parse()?

I have an array that is printed in JSON
[{"Name":"John Ranniel","Age":"19","City":"Manila"},{"Contact":"09197875656","Relation":"Sister"}]
For some reason, I divided the JSON into two parts.
In javascript I used JSON.parse() to decode the JSON above.
for example:
var arr = JSON.parse(response); //The response variable contains the above JSON
alert(arr[0].Name) //Still it outputs John Ranniel, but If i change the content of the alert box on the second part of the JSON,
alert(arr[1].Contact) // It has no output, I don't know if there is a problem with the index of the array.

Make sure your JSON is a string type:
'[{"Name":"John Ranniel","Age":"19","City":"Manila"},{"Emergency Contact":"09197875656","Relation":"Sister"}]'
and then, you can use,
var arr = JSON.parse(response); //The response variable contains the above JSON
console.log(arr[0].Name);
console.log(arr[1]['Emergency Contact']); // There is no 'Contact' property iun your object, and you should use this when there's a space in the name of the property.
See:
var response = '[{"Name":"John Ranniel","Age":"19","City":"Manila"},{"Emergency Contact":"09197875656","Relation":"Sister"}]';
var arr = JSON.parse(response);
console.log(arr[0].Name);
console.log(arr[1]['Emergency Contact']); // There is no 'Contact' property iun your object, and you should use this when there's a space in the name of the property.

You are trying to parse something which is already a JavaScript object, and does not need to be parsed. You need to parse JSON strings. This is not a JSON string. It's a JavaScript object.
Consider the following:
JSON.parse([1,2])
This will coerce the array [1,2] into the string "1,2". JSON.parse will then choke on the ,, since it doesn't belong there in a valid JSON string.
In your case the object will be coerced to the string
"[object Object],[object Object]"
JSON.parse will accept the leading [ as the beginning of the array, then throw on the following character, the o, since it does not belong there in a proper JSON string.
But you say that the JSON.parse worked and resulted in arr. In other words, the parameter you fed to JSON.parse apparently was a string, and was parsed correctly. In that case, the alerts will work fine.

Your JSON structure is array, must be parse to JSON,use JSON.stringify parse this to JSON:
var json = [{"Name":"John Ranniel","Age":"19","City":"Manila"},{"Contact":"09197875656","Relation":"Sister"}];
var str = JSON.stringify(json);
console.log(json);
var arr = JSON.parse(str);
alert(arr[0].Name) //Still it outputs John Ranniel, but If i change the content of the alert box on the second part of the JSON,
alert(arr[1].Contact) // It has no output, I don't know if there is a problem with the index of the array.
Demo: Link
This JSON is array, you can use directly:
var json = [{"Name":"John Ranniel","Age":"19","City":"Manila"},{"Contact":"09197875656","Relation":"Sister"}];
alert(json[0].Name);
alert(json[1].Contact);

Javascript JSON.parse or directly access

When we can read a property directly from string:
var data = {"id":1,"name":"abc","address":{"streetName":"cde","streetId":2}};
console.log(data.address.streetName); // cde
Why do people use JSON.parse:
var obj = JSON.parse(data);
console.log(obj.address.streetName); // cde

It is not a string, but Javascript object. String is given below
var data = '{"id":1,"name":"abc","address":{"streetName":"cde","streetId":2}}';
to make it object we use JSON.parse
var obj = JSON.parse(data);
console.log(obj.address.streetName); // cde

In your first example, data is an object, but in your second example, data is a JSON string.
That's a major difference. You could call eval(data) to parse a JSON string, but that's very unsafe.

JSON.parse() expects a string. More specifically, a string with a JSON-encoded piece of data.
If it's applied to an object then it's an error, the source of which is probably the common confusion that seems to exist between JavaScript objects and the JSON format.

javascript split and JSON.parse

I want to parse array in JSON format using javascript. I have written following code.
var data = "abc, xyz, pqr";
var data_array = data.split(',');
var data_parsed = JSON.parse(data_array);
alert(data_parsed);
It gives me the error of JSON.parse
I have no idea how to resolve this javascript error.

You don't have any JSON, so don't use JSON.parse. Once you split you already have an array whose elements could be used directly:
var data = "abc, xyz, pqr";
var data_array = data.split(',');
alert(data_array[0]);
and if you want to convert this array to a JSON string you could do this:
var json = JSON.stringify(data_array);
alert(json);

That's because "abc, xyz, pqr" isn't valid JSON. Plus, JSON.parse() is meant to parse JSON strings, not arrays. What are you trying to do, perhaps we can better assist.

This is actually a convenient short cut to json processing if you only need a smaller set of variables.
PHP:
return $var1 .','. $var2 .',some_string_value.';
Javascript:
var myReturnArray = returnValue.split(',');