Using inheritance with functional programming. This example was taken from the book "Javascript: The Good Parts".

functional_programming.js

var mammal = function(spec){
  var that = {};
  
  that.getName = function( ){
    return spec.name;
  };
  
  that.says = function( ){
    return spec.saying || '';
  };
  
  return that;
};

var myMammal = mammal({ name: 'Herb' });
console.log(myMammal.getName( ));
console.log(myMammal.says( ));


/*====================================*/

var cat = function(spec){
    spec.saying = spec.saying || 'meow';
    var that = mammal(spec);
    
    that.purr = function(n){
      var i, s = '';
      for(i=0; i<n; i+=1){
        if(s) s += '-';
        s += 'r'
      }
      
      return s;
    };
    
    that.getName = function( ){
      return that.says( ) + ' ' + spec.name + ' ' + that.says( );
    }
    
    return that;
};

var myCat = cat({ name: 'Henrietta' });

console.log(myCat.getName( ));
console.log(myCat.says( ));