JSON.stringify（ComplexArray）返回一个空字符串

Question

I have the following JavaScript which utilises JQuery and Knockout (I have specific reasons for using the 2 together)

$(document).ready(
  function () {
      var Crime = function (Id, CaseNumber, DateOfIncident, Description) {
          var self = this;
          self.Id = Id;
          self.CaseNumber = CaseNumber;
          self.DateOfIncident = DateOfIncident;
          self.Description = Description;
      }

      var CrimesViewModel = function () {
          var self = this;
          //Data
          self.items = ko.observableArray()

          //operations
          addCrime = function () {
              if ($("#AddCrimeForm").valid()) {
                  crime = new Crime(0,
                      $("#AddCrimeForm #CaseNumber").val(),
                      $("#AddCrimeForm #DateOfIncident").val(),
                      $("#AddCrimeForm #Description").val());

                  self.items.push(this.crime);

                  $("#AddCrimeForm #CaseNumber").val("");
                  $("#AddCrimeForm #DateOfIncident").val("");
                  $("#AddCrimeForm #Description").val("");
              }
          }

          self.removeCrime = function (item) {
              self.items.remove(item);
          }

          loadCrimes = function (JSONstring) {
              try {
                  self.JSONItems = JSON.parse(JSONstring);
                  if (self.JSONItems != null)
                      if (self.JSONItems != null)
                          for (i = 0; i < self.JSONItems.length; i++)
                              self.items.push(self.JSONItems[i]);
              }
              catch (e) {
                  alert(e.message + "\n\n" + e.description + "\n\n" + e.stack)
              }
          }

          getCrimes = function () {
              var self = this;
              return JSON.stringify(self.items);
          }

      }

      var CrimesVM = new CrimesViewModel()

      ko.applyBindings(CrimesVM, $("#CrimeList")[0])

  }
);

As illustrated by the above code, I have a ViewModel which basically consists of an array containing Crime objects.

It is the intent of the getCrimes() function to, when called, serialise the array into JSON.

The getCrimes() function, unfortunately, returns an empty string, due to the fact that JSON.stringify(self.items) returns an empty string.

Any idea what I am doing wrong here?

**

UPDATE

**

Here is the working code, based on the answer given below:

$(document).ready(
  function () {
      var Crime = function (Id, CaseNumber, DateOfIncident, Description) {
          var self = this;
          self.Id = Id;
          self.CaseNumber = CaseNumber;
          self.DateOfIncident = DateOfIncident;
          self.Description = Description;
      }

      var CrimesViewModel = function () {
          var self = this;
          //Data
          self.items = ko.observableArray()

          //operations
          addCrime = function () {
              if ($("#AddCrimeForm").valid()) {
                  crime = new Crime(0,
                      $("#AddCrimeForm #CaseNumber").val(),
                      $("#AddCrimeForm #DateOfIncident").val(),
                      $("#AddCrimeForm #Description").val());

                  self.items.push(this.crime);

                  //Update the correspoding hidden field
                  $("#CrimeCollection_New").val(ko.toJSON(self));

                  $("#AddCrimeForm #CaseNumber").val("");
                  $("#AddCrimeForm #DateOfIncident").val("");
                  $("#AddCrimeForm #Description").val("");                  
              }
          }

          self.removeCrime = function (item) {
              self.items.remove(item);
              //Update the correspoding hidden field
              $("#CrimeCollection_New").val(ko.toJSON(self));
          }

          loadCrimes = function (JSONstring) {
              try {
                  self.JSONItems = JSON.parse(JSONstring);
                  if (self.JSONItems != null)
                      if (self.JSONItems != null)
                          for (i = 0; i < self.JSONItems.length; i++)
                              self.items.push(self.JSONItems[i]);
              }
              catch (e) {
                  alert(e.message + "\n\n" + e.description + "\n\n" + e.stack)
              }
          }



      }

      var CrimesVM = new CrimesViewModel()

      ko.applyBindings(CrimesVM, $("#CrimeList")[0])

  }
);

Answer 1

Because self.items is a Knockout observable, you should use the Knockout function .toJS() to get the values: ko.toJS(self.items) .

Or, if you want to convert the items directly to JSON, you can use .toJSON() .

Knockout: Loading and saving JSON data