Fix truncated JSON data.

FixJson.js

var json = '...'; // your truncated json data here

var chunk = json;

var m, q = false;
var stack = [];

while (m = chunk.match(/[^\{\[\]\}"]*([\{\[\]\}"])/)) {
  switch (m[1]) {
    case '{':
      stack.push('}');
    break;
    case '[':
      stack.push(']');
    break;

    case '}':
    case ']':
      stack.pop();
    break;

    case '"':
      if (!q) {
        q = true;
        stack.push('"');
      } else {
        q = false;
        stack.pop();
      }
    break;
  }
  chunk = chunk.substring(m[0].length);
}

if (chunk[chunk.length-1] === ':') {
  json += '""';
}

while (stack.length) {
  json += stack.pop();
}

// JSON.parse(json);

Does only work for cuts on end, not for booleans, not for escaped special chars - yet.