updating KO model from json

gistfile1.js

// map the keys in json to the properties on your model
var desiredKeys = {
  "foo": "foo",
  "bar": "bar"
};

Object.defineProperty(self, 'updateFromJson', {
  enumerable: true,
  value: function (data) {
    Object.keys(data)
      .forEach(function (key) {
        var modelKey = desiredKeys[key];
        if (!modelKey) return;

        if ( !_.isEqual(self[modelKey], data[key]) )
          self[modelKey] = data[key];  // I can use = syntax because I use Object.defineproperty with setters
      });
  }
});