Practice to implement the Buffer pattern.

Buffer.js

Buffer = {
  commands: [],
  
  add: function(fn) {
    var commands = this.commands;
    
    var next = function() {
      commands.shift();
      if (commands.length) commands[0](next);
    };
    
    commands.push(fn);
   
    if (this.commands.length == 1) fn(next);
     
    return this;
  }
};

var log_1 = function(next) {
  console.log('entry log one');
  next();
};

var log_2 = function(next) {
  console.log('entry log two');
  next();
};

var log_3 = function(next) {
  console.log('entry log three');
  next();
};

Buffer.add(log_1).add(log_2).add(log_3);