Fix possibility to create huge arrays of null objects.

[abecciu]

This fixes a serious bug. Someone hitting an app with a param like a[999999999]=1 could make a node process crash by running out memory very quickly.

Example:

var qs = require('qs');

console.log(qs.parse('a[999999999]=1'));

[abecciu]

@visionmedia any feedback on this?

[tj]

hmmm they're sparse internally, for example qs.parse('foo[100000000000000000000000000000000000000000000]=1') wont exhaust memory, however for iteration and console.log() this is obviously not ideal :D haha I'll check out the fix

[tj]

instead of altering the already super messy functions a bunch we could wrap the parseObject response with something like:

function sparse(obj) {
  if (Array.isArray(obj)) {
    var ret = [];
    for (var i in obj) ret.push(obj[i]);
    return ret;
  }

  for (var key in obj) {
    obj[key] = sparse(obj[key]);
  }

  return obj;
}

and make sure it recurses properly

[abecciu]

@visionmedia sounds like a very clean solution. However, if I understand correctly, you'd have to iterate over potentially very long arrays. And that consumes a lot of cpu time.

[tj]

@abecciu for/in just iterates the hash keys

[abecciu]

Oh didn't know that it works like that even in arrays. Great then! I'll make the change.

[abecciu]

@visionmedia done! Way cleaner now. Thanks for the feedback! :)

[tj]

merged! thanks man

[caligo-mentis]

So. This PR breaks my production code when I try to send array which starts with non-zero index and expect what non-defined array elements will be undefined. How should I send empty array element to server now? Of course, I can send JSON instead of form data but this behavior of querystring library was not expected.