jQuery ajax returned data: json and html mix?

Question

I have this ajax request to get the data from my server, and the dataType is always html by default. But sometimes it would return json from the server, so I want to check if the returned data is html then execute A else execute B. Is it possible?

My jquery,

 $.ajax({
     type: "GET",
     dataType: "html",
     url: request_url,
     context: $('#meat'),
     async: true,
     beforeSend: function () {},
     success: function (returndata, status, jqXHR) {
         if ($.parseJSON(returndata) === false) A;
         else B.
     }
 });

I get this error when the returned data is html,

SyntaxError: JSON.parse: unexpected character

So how can I make this code versatile?

yes for the json data. but i dont use json_encode if the returned data is html. — Run
– Run, Commented Dec 23, 2013 at 12:15
you can try this: dataType: "json" || "html", and you can try using typeof() method for the return data that if that is object the process it as json. — Jai
– Jai, Commented Dec 23, 2013 at 12:18

geedubb · Accepted Answer · 2013-12-23 12:23:32Z

6

I'm not sure if there is a better way, but you could try... catch

$.ajax({
      type:       "GET",
      url:        request_url,
      context:    $('#meat'),
      async:      true,
      beforeSend: function() {
      },
      success: function (returndata, status, jqXHR) {
        var parsed;
        try
        {
            parsed = $.parseJSON(returndata);
            // Execute B
        }
        catch(e)
        {
           // treat as html then
           // do parsing here
           parsed = returnData;
           // Execute A
        }
      }

});

answered Dec 23, 2013 at 12:23

geedubb

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Community · Accepted Answer · 2017-05-23 12:19:09Z

4

Essentially, your code is just plain wrong - your serverside API is violating all principles of predictability if the return type can vary in an inconsistent manner. Your code should never have to guess at the type of the returned data.

Having said that, a simple try/catch will help as a workaround for the erratic behaviour if you don't want to fix it. Ie.

try {
    if ($.parseJSON(returndata) === false) A;
} catch(e) {
    // Treat as HTML here.
}

It's not pretty, but that's what you get for having an unpredictable API that isn't pretty to begin with.

edited May 23, 2017 at 12:19

CommunityBot

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answered Dec 23, 2013 at 12:22

Niels Keurentjes

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2 Comments

Run Over a year ago

thanks. but this line if ($.parseJSON(returndata) === false) does not do anything when I pass a json data in.

Niels Keurentjes Over a year ago

I just copied that part from your code - my answer is about circumventing the error, not about other problems you may or may not have ;)

Community · Accepted Answer · 2017-05-23 12:11:33Z

-1

may be you need to handle it like this

try{
var response=jQuery.parseJSON('response from server');
if(typeof response =='object')
 {
    //control would reach this point if the data is returned as json
 }
 else
 {
    //control would reach this point if data is plain text  
     if(response ===false)
     {
         //the response was a string "false", parseJSON will convert it to boolean false
     }
     else
     {
          //the response was something else
     }
 }
}
catch(exp){
    //controls reaches here, if the data is html
}

Since you need to check the html data as well, you may need to take care of this,

Might also need to use a try / catch for exceptions if it is possible that parseJSON is going to be dealing with something other than JSON values (i.e. HTML)

REF:How can I check if a value is a json object?

EDIT:Edited to make code more precise towards solution

edited May 23, 2017 at 12:11

CommunityBot

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answered Dec 23, 2013 at 12:23

dreamweiver

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3 Comments

Niels Keurentjes Over a year ago

Won't work, his whole core problem is that parseJSON throws an error, so most of your code is 'unreachable' in the problem case.

dreamweiver Over a year ago

@NielsKeurentjes: thats the reason i added a message(in italic font) saying that the parseJSON need to be enclosed within try catch block to handle the exception in case html data is returned .

dreamweiver Over a year ago

@NielsKeurentjes: I have edited the answer, i guess now its fine

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