This simple gist will parse JSON data and convert datetime string to proper date objects. It can be extended to include other date string formats.

JsonDates.js

// ******** Date Parsing ********
var jsonDates = {
  dtrx2: /\d{4}-\d{2}-\d{2}/,
  parse: function(obj){
      var parsedObj = JSON.parse(obj);
      return this.parseDates(parsedObj);
  },
  parseDates: function(obj){
    // iterate properties
    for(pName in obj){
      
      // make sure the property is 'truthy'
      if (obj[pName]){
        var value = obj[pName];
        // determine if the property is an array
        if (Array.isArray(value)){
          for(var ii = 0; ii < value.length; ii++){
            this.parseDates(value[ii]);
          }
        }
        // determine if the property is an object
        else if (typeof(value) == "object"){
          this.parseDates(value);
        }
        // determine if the property is a string containing a date
        else if (typeof(value) == "string" && this.dtrx2.test(value)){
          // parse and replace
          obj[pName] = new Date(obj[pName]);
        }
      }
    }

    return obj;
  }
};