How can I split a string containing n concatenated json string in javascript/nodejs?

Question

Let's say I receive this string from a socket server (which I cannot control):

{"data":{"time":"2016-08-08T15:13:19.605234Z","x":20,"y":30}}{"data":{"time":"2016-08-08T15:13:19.609522Z","x":30,"y":40}}

I cannot use JSON.parse since it contains 2 Json string so how can I split into

var jsonString1 = {"data":{"time":"2016-08-08T15:13:19.605234Z","x":20,"y":30}}

and

var jsonString2 = {"data":{"time":"2016-08-08T15:13:19.609522Z","x":30,"y":40}}

Note: I may have 1 to n Json strings concatenated in fact

So you have an array of jsons, to start with. You should then be parsing the array of jsons first, and then each json separately.This is how I do it with Newtonsoft's library for .net. — Veverke, Aug 08 '16 at 15:25
I would loop through each character of the string, count the number of '{' and '}' characters. Once the amount of '{' are equal to the amount of '}' you know your first JSON string has ended. Except ofcourse when you start the loop and the amount for both of them is 0 — Alain Stoffels, Aug 08 '16 at 15:26
How about splitting the original string using `split("}{")` ? — Rajaprabhu Aravindasamy, Aug 08 '16 at 15:26

score 9 · Accepted Answer · answered Aug 08 '16 at 15:33

9

You could just do:

var data = '{"data":{"time":"2016-08-08T15:13:19.605234Z","x":20,"y":30}}{"data":{"time":"2016-08-08T15:13:19.609522Z","x":30,"y":40}}';

var sanitized = '[' + data.replace(/}{/g, '},{') + ']';
var res = JSON.parse(sanitized);

console.log(res);

However, this will fail if one of the objects contains the }{ pattern in a string.

answered Aug 08 '16 at 15:33

Arnauld

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It works but I'd like to print x, y : see https://jsfiddle.net/ys6j038q/ – user310291 Aug 08 '16 at 16:45
I ask complementary question here: http://stackoverflow.com/questions/38834601/how-to-get-x-y-from-nest-object – user310291 Aug 08 '16 at 16:49
What you get here is an array of objects. If you want to access the `x` property of the second object, you'd have to do `res[1].data.x`. – Arnauld Aug 08 '16 at 16:55

score 4 · Answer 2 · answered Aug 08 '16 at 15:26

4

You can split them by the occurrence of } followed directly by { (ignoring whitespace).

var parts = str.split(/\}\s*\{/g);
for(var i = 0; i < parts.length; i++) {
  var part = parts[i].trim();

  if(part[0] !== '{') part = '{' + part;
  if(part[part.length-1] !== '}') part += '}';

  var json = JSON.parse(part);
}

answered Aug 08 '16 at 15:26

micah

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But each json contains nested objects. What if data is : {} ? – Veverke Aug 08 '16 at 15:27
@Veverke Those objects would be split by a comma. – micah Aug 08 '16 at 15:29
I was trying something less hard-wired. If this solves the issue, however, it's the answer :) – Veverke Aug 08 '16 at 15:30
@Veverke JSON doesn't allow an unescaped `}{` anywhere outside of strings. [The spec](http://www.json.org/) is very concise, so you can check. – ssube Aug 08 '16 at 15:30
Why anyway the source of this string does not return an array of jsons ? I would expect a comma separating each distinct js object enclosing the "data" property. If he has control over the source, I would fix this, and make things more intuitive. – Veverke Aug 08 '16 at 15:32

score 1 · Answer 3 · answered Aug 08 '16 at 15:39

Just split when /\}\s*\{/g and pass a value to fill to the Array.prototype.reduce function.

var str = '{"data":{"time":"2016-08-08T15:13:19.605234Z","x":20,"y":30}}{"data":{"time":"2016-08-08T15:13:19.609522Z","x":30,"y":40}}'

var data = (function(input) {
  let odd = true;
  
  return input.split(/\}\s*\{/g).reduce(function(res, part, i) {
    if(odd) {
      part += "}";
    } else {
      part = "{" + part;
    }
    
    odd = !odd;
    
    res[i] = JSON.parse(part);
    
    return res;
  }, {});
})(str)

console.log("data:", data);

How can I split a string containing n concatenated json string in javascript/nodejs?

3 Answers3

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