javascript - json stringify circular objects in 50 lines of code this code recursively traverses a json array / object. it will stringify all circular objects it encounters for first time and cache their references. that way it can avoid them again in the future.

gistfile1.js

/*jslint indent: 2, nomen: true, regexp: true, stupid: true*/
(function () {
  'use strict';

  var circularObject, exports = {};

  exports.jsStringifyCircular = function (oo, arr) {
    //// stringify circular objects
    var ii, kk, out, vv;
    arr = arr || [];
    if (oo) {
      for (ii = 0; ii < arr.length; ii += 1) {
        if (oo === arr[ii]) {
          oo = '[Circular]';
          break;
        }
      }
    }
    try {
      return JSON.stringify(oo);
    } catch (err) {
    }
    //// fallback
    arr.push(oo);
    out = '';
    //// array
    if (Array.isArray(oo)) {
      for (ii = 0; ii < oo.length; ii += 1) {
        vv = exports.jsStringifyCircular(oo[ii], arr);
        if (vv !== undefined) {
          out += vv + ',';
        }
      }
      return '[' + (out ? out.slice(0, -1) : out) + ']';
    }
    //// object
    kk = Object.keys(oo).sort();
    for (ii = 0; ii < kk.length; ii += 1) {
      vv = exports.jsStringifyCircular(oo[kk[ii]], arr);
      if (vv !== undefined) {
        out += JSON.stringify(kk[ii]) + ':' + vv + ',';
      }
    }
    return '{' + (out ? out.slice(0, -1) : out) + '}';
  };

  //// test
  circularObject = [1, 2, 3, 4];
  circularObject.push({'foo': circularObject});
  console.log(exports.jsStringifyCircular(circularObject));
}());