Using a WeakMap to store instance data properties

weakmap-for-instance-data.js

(function( exports ) {

var records = new WeakMap();

function Record( data ) {
  records.set(this, data);
}

Record.prototype.save = function() {
 ... persist the things
};

Record.prototype.get = function( field ) {
  return records.get(this)[ field ];
};

Record.prototype.set = function( field, value ) {
  var data = records.get(this);

  data[ field ] = value;

  records.set(this, data);
};

exports.Record = Record;

}(this));


var rec = new Record({ save: "no problem!" });

// good to go :D
rec.save();