Extract data from JSON object on the server side

Within my web service, I have a method that returns a JSON object:

{name:'xx'}

When making an Ajax request and parsing the response with 'eval', I encountered an issue.

onComplete:function(req){
  var data=eval(req.responseText);
  //perform actions based on data
}

However, I was unable to retrieve the 'data' as intended.

Upon returning the following string instead:

[{name:'xx'}]

It worked, allowing me to obtain the 'data' as an array.

After researching through Google, I learned this is due to the presence of '{' in the return string.

This led me to question if there is a different approach to return a JSON object?

javascriptjson

Answer №1

Consider utilizing JSON.parse or the jquery function $.parseJSON in place of using eval.
Furthermore, if you are already employing jquery, you have the option to use the built-in ajax method which will automatically fetch and parse the response as a JSON object: $.getJson.

If you are adamant about not altering your existing "logic", you could attempt evaluating your response with additional brackets like so: 

var data = eval('(' + req.responseText + ')');

Answer №2

Take a look at this informative blog post about JSON hijacking. The author provides a detailed explanation of the issue you're encountering.

If you've come across code like the snippet below in relation to JSON:

eval('('+JSON_DATA+')');

Pay attention to the use of parentheses at the beginning and end. This is done to ensure that JavaScript interprets the data as an object rather than a block statement. Without these parentheses, attempting to execute JSON data without proper syntax could result in a syntax error.

...more details on this topic...

Instead of enclosing your JSON response in (), it is recommended to utilize JSON.parse or $.parseJSON as suggested by gion_13. Avoid using Eval for this purpose.

Additionally, as pointed out by quentin in the comments, make sure to modify the format of the JSON you are returning as it appears to be invalid. Remember to enclose both keys and values in quotes.

Answer №3

Success! I was able to make it function properly, and now 'data' is retrieved as an array.

This is the expected outcome. The use of [] signifies the declaration of an array. In order to return the inner object, simply use {name: 'XX'}.

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