[javascript] javascript object max size limit

I'm trying to pass a JavaScript variable to the server-side using jquery.ajax method.

I'm trying to create a json string, but when the length of variable reaches 10000, no more data is appended to the string.

var jsonObj = '{"code":"' + code + '","defaultfile":"' + defaultfile + '","filename":"' + currentFile + '","lstResDef":[';
        $.each(keys, function(i, item) {
            i = i + 1;
            var value = $("#value" + i).val();
            var value = value.replace(/"/g, "\\\"");
            jsonObj = jsonObj + '{';
            jsonObj = jsonObj + '"Key":' + '"' + Encoder.htmlEncode($(this).html()) + '"' + "," + '"Value"' + ':' + '"' + Encoder.htmlEncode(value) + '"';
            jsonObj = jsonObj + '},';
            alert(jsonObj);             
        });          

        jsonObj = jsonObj + ']}';

Here, when the character length of the var jsonObj is 10000, the values following that is not appended.

It looks like there is some limit about that.

Step 1 is always to first determine where the problem lies. Your title and most of your question seem to suggest that you're running into quite a low length limit on the length of a string in JavaScript / on browsers, an improbably low limit. You're not. Consider:

var str;

document.getElementById('theButton').onclick = function() {
  var build, counter;

  if (!str) {
    str = "0123456789";
    build = [];
    for (counter = 0; counter < 900; ++counter) {
      build.push(str);
    }
    str = build.join("");
  }
  else {
    str += str;
  }
  display("str.length = " + str.length);
};

Live copy

Repeatedly clicking the relevant button keeps making the string longer. With Chrome, Firefox, Opera, Safari, and IE, I've had no trouble with strings more than a million characters long:

str.length = 9000
str.length = 18000
str.length = 36000
str.length = 72000
str.length = 144000
str.length = 288000
str.length = 576000
str.length = 1152000
str.length = 2304000
str.length = 4608000
str.length = 9216000
str.length = 18432000

...and I'm quite sure I could got a lot higher than that.

So it's nothing to do with a length limit in JavaScript. You haven't show your code for sending the data to the server, but most likely you're using GET which means you're running into the length limit of a GET request, because GET parameters are put in the query string. Details here.

You need to switch to using POST instead. In a POST request, the data is in the body of the request rather than in the URL, and can be very, very large indeed.

you have to put this in web.config :

<system.web.extensions>
    <scripting>
      <webServices>
        <jsonSerialization maxJsonLength="50000000" />
      </webServices>
    </scripting>
  </system.web.extensions>