javascript object 转换为 json格式 toJSONString

Object.prototype.toJSONString = function () {

        var a = ['{'],  // The array holding the text fragments.

            b,          // A boolean indicating that a comma is required.

            k,          // The current key.

            v;          // The current value.



        function p(s) {



            // p accumulates text fragment pairs in an array. It inserts a comma before all

            // except the first fragment pair.



            if (b) {

                a.push(',');

            }

            a.push(k.toJSONString(), ':', s);

            b = true;

        }



        // Iterate through all of the keys in the object, ignoring the proto chain.



        for (k in this) {

            if (this.hasOwnProperty(k)) {

                v = this[k];

                switch (typeof v) {



                // Values without a JSON representation are ignored.



                case 'undefined':

                case 'function':

                case 'unknown':

                    break;



                // Serialize a JavaScript object value. Ignore objects that lack the

                // toJSONString method. Due to a specification error in ECMAScript,

                // typeof null is 'object', so watch out for that case.



                case 'object':

                    if (this !== window)

                    {

                      if (v) {

                          if (typeof v.toJSONString === 'function') {

                              p(v.toJSONString());

                          }

                      } else {

                          p("null");

                      }

                    }

                    break;

                default:

                    p(v.toJSONString());

                }

            }

        }



          // Join all of the fragments together and return.



        a.push('}');

        return a.join('');

    };