title: knockout.js dynamic field binding with variable
body: <p>Is there a way to dynamically replace the field being written to and read from in the ko.computed? For example, with this function, I want to replace the self.JobStartDate with a variable fieldname that I could pass in:  </p>
  
  <pre><code>function Job(data) {
      var self = this;
      ko.mapping.fromJS(data, {}, this); 
  
      var computedDateFn = {
          read: function() {
              return formatDate(ko.utils.unwrapObservable(self.JobStartDate), true);
          },
  
          write: function(value) {
              var jsonDate = "/Date(" + Date.parse(value).getTime();
              self.JobStartDate(jsonDate);
          }
      }
  
      this.formattedStartDate = ko.computed(computedDateFn);
      this.formattedEndDate = ko.computed(computedDateFn); // this guy would need the field it writes to/reads from to be self.JobEndDate
  }
  </code></pre>