Mixins(примеси) From translate: http://habrahabr.ru/post/147901/, original article: https://javascriptweblog.wordpress.com/2011/05/31/a-fresh-look-at-javascript-mixins/

classic_mixin.js

var Circle = function() {};
Circle.prototype = {
  area: function() {
    return Math.PI * this.radius * this.radius;
  },
  grow: function() {
    this.radius++;
  },
  shrink: function() {
    this.radius--;
  }
};

// or more short variant
var circleFns = {
  area: function() {
    return Math.PI * this.radius * this.radius;
  },
  grow: function() {
    this.radius++;
  },
  shrink: function() {
    this.radius--;
  }
};

function extend(destination, source) {
  for (var k in source) {
    if (source.hasOwnProperty(k)) {
      destination[k] = source[k];
    }
  }
  return destination; 
}

var RoundButton = function(radius, label) {
  this.radius = radius;
  this.label = label;
};

extend(RoundButton.prototype, circleFns);
extend(RoundButton.prototype, buttonFns);
//etc. ...

functional_minx_with_caching.js

// adding caching
var asRectangle = (function() {
  function area() {
    return this.length * this.width;
  }
  function grow() {
    this.length++;
    this.width++;
  }
  function shrink() {
    this.length--;
    this.width--;
  }
  return function() {
    this.area = area;
    this.grow = grow;
    this.shrink = shrink;
    return this;
  };
})();

var RectangularButton = function(length, width, label, action) {
  this.length = length;
  this.width = width;
  this.label = label;
  this.action = action;
};

asRectangle.call(RectangularButton.prototype);

var button3 = new RectangularButton(4, 2, 'delete', function() {return 'deleted'});
button3.area(); //8
button3.grow();
button3.area(); //15

functional_mixin.js

var asCircle = function() {
  this.area = function() {
    return Math.PI * this.radius * this.radius;
  };
  this.grow = function() {
    this.radius++;
  };
  this.shrink = function() {
    this.radius--;
  };
  return this;
};

var asButton = function() {
  this.hover = function(bool) {
    bool ? mylib.appendClass('hover') : mylib.removeClass('hover');
  };
  this.press = function(bool) {
    bool ? mylib.appendClass('pressed') : mylib.removeClass('pressed');
  };
  this.fire = function() {
    return this.action();
  };
  return this;
};

var Circle = function(radius) {
    this.radius = radius;
};
asCircle.call(Circle.prototype);
var circle1 = new Circle(5);
circle1.area(); //78.54


// and more hard complex example with options
var asOval = function(options) {
  this.area = function() {
    return Math.PI * this.longRadius * this.shortRadius;
  };
  this.ratio = function() {
    return this.longRadius/this.shortRadius;
  };
  this.grow = function() {
    this.shortRadius += (options.growBy/this.ratio());
    this.longRadius += options.growBy;
  };
  this.shrink = function() {
    this.shortRadius -= (options.shrinkBy/this.ratio());
    this.longRadius -= options.shrinkBy;
  };
  return this;
}

var OvalButton = function(longRadius, shortRadius, label, action) {
  this.longRadius = longRadius;
  this.shortRadius = shortRadius;
  this.label = label;
  this.action = action;
};

asButton.call(OvalButton.prototype);
asOval.call(OvalButton.prototype, {growBy: 2, shrinkBy: 2});

var button2 = new OvalButton(3, 2, 'send', function() {return 'message sent'});
button2.area(); //18.84955592153876
button2.grow();
button2.area(); //52.35987755982988 
button2.fire(); //'message sent'

functional_mixin_with_curry.js

// adding curry
Function.prototype.curry = function() {
  var fn = this;
  var args = [].slice.call(arguments, 0);
  return function() {
    return fn.apply(this, args.concat([].slice.call(arguments, 0)));
  };
}

var asRectangle = (function() {
  function area() {
    return this.length * this.width;
  }
  function grow(growBy) {
    this.length += growBy, this.width +=growBy;
  }
  function shrink(shrinkBy) {
    this.length -= shrinkBy, this.width -= shrinkBy;
  }
  return function(options) {
    this.area = area;
    this.grow = grow.curry(options['growBy']);
    this.shrink = shrink.curry(options['shrinkBy']);
    return this;
  };
})();

asRectangle.call(RectangularButton.prototype, {growBy: 2, shrinkBy: 2});

var button4 = new RectangularButton(2, 1, 'add', function() {return 'added'});
button4.area(); //2
button4.grow();
button4.area(); //12