styles-with-prototypes.js

function Button() {}
Button.prototype = {
  color: 'blue',
  border: '1px solid black'
};

// use classical inheritance or something like functional mixins to replicate
// the cascading nature of stylessheets
function ButtonActive() {}
ButtonActive.prototype = Object.create(Button.prototype);
ButtonActive.prototype.color = 'red';

// now we may save some memory since `border` is only defined on
// Button.prototype
//
// also multiple react component instances can share `buttonStyle` and
// `buttonActiveStyle`, we don't need to instantiate a new style object every
// time.
var buttonStyle = new Button();
var buttonActiveStyle = new ButtonActive();