JavaScript GOF

.Title

JavaScript GOF

0.core

 // Normal Function
 function startAnimation() {
   // ...
 };

 function StopAnimation() {
   // ...
 };

 // Anim Class
 var Anim = function() {
   // ...
 };
 // Add function to Anim
 Anim.prototype.start = function() {};
 Anim.prototype.stop = function() {};

 // Another Way to add function to a class
 Anim.prototype = {
   start: function() {
     // ...
   },

   stop: function() {
     // ...
   }
 };

 // Add a method to the Function object that can be used to declare methods.
 Function.protype.method = function(name, fn) {
   this.prototype[name] = fn;
   return this;
 };

 var Anim = function() {};
 Anim.method('start', function() {
   // ...
 });
 Anim.method('stop', function() {
   // ...
 });

 Anim.
 method('start', function() {
   // ...
 }).
 method('stop', function() {
   // ...
 });

 // Function as Object
 (function() {
   // ...
 })()

 (function(a, b) {
   // ...
   return a + b
 })(1, 2)

 // Add attribute to a Object
 function aFunction() {};
 aFunction.aAttribute = 0;

 function person() {
   this.name = "Aaron";
   this.age = 14;
 };
 person.prototype = {
   getName: function() {
     return this.name;
   },
   getAge: function() {
     return this.age;
   }
 }

0.encapsulation.js

// 1.
var Book = function(isbn,title,author){
  this.setIsbn(isbn);
  this.setTitle(title);
  this.setAuthor(author);
};

Book.prototype = {
  setIsbn: function(isbn){
    this.isbn = isbn;
  },
  getIsbn: function(){
    return this.isbn;
  },
  setTitle: function(title){
    this.title = title;
  },
  getTitle: function(){
    return this.title;
  },
  setAuthor: function(author){
    this.author = author;
  },
  getAuthor: function(){
    return this.author;
  }
};

// 2.
var Book = function(isbn,title,author){
  this.setIsbn(isbn);
  this.setTitle(title);
  this.setAuthor(author);
};

Book.prototype = {
  setIsbn: function(isbn){
    this._isbn = isbn;
  },
  getIsbn: function(){
    return this._isbn;
  },
  setTitle: function(title){
    this._title = title;
  },
  getTitle: function(){
    return this._title;
  },
  setAuthor: function(author){
    this._author = author;
  },
  getAuthor: function(){
    return this._author;
  }
};

// 3.
var Book = function(newIsbn,newTitle,newAuthor){
  var isbn,title,author;

  this.setIsbn=function(newIsbn){
    isbn = newIsbn;
  };
  this.getIsbn=function(){
    return isbn;
  };
  this.setTitle=function(newTitle){
    title = newTitle;
  };
  this.getTitle=function(){
    return title;
  };
  this.setIsbn=function(newAuthor){
    author = newAuthor;
  };
  this.getIsbn=function(){
    return author;
  };
}

// 4.
var Book = (function(){
  // ...

  return function(newIsbn,newTitle,newAuthor){
    var isbn,title,author;

    this.setIsbn=function(newIsbn){
      isbn = newIsbn;
    };
    this.getIsbn=function(){
      return isbn;
    };
    this.setTitle=function(newTitle){
      title = newTitle;
    };
    this.getTitle=function(){
      return title;
    };
    this.setIsbn=function(newAuthor){
      author = newAuthor;
    };
    this.getIsbn=function(){
      return author;
    };
  };
})();

// Constant

// 1.
var Book = function(){
  var constants = ["key1": "1","key2": "2","key3": "3"];

  this.getConstant = function(key){
    return constants[key];
  };
};

Book.getConstant("key1");

// 2.
var Book = (function(){
  var constants = ["key1": "1","key2": "2","key3": "3"];

  var con = function(){};
  con.getContant = function(name){
    return constants[name];
  };

  return con;
})();

Book.getConstant("key1");

0.interface.js

// 1. 用注释描述接口

/*

interface Composite {
  function add(child);
  function remove(child);
  function getChild(index);
}

*/

// 2. 用属性模仿接口
// 
// 使用特定的方法来对特定的对象进行检查，看其是否实现了一组对应的方法，从而判断是否符合接口的要求。
function implements(object) {
  for (var i = 1; i < arguments.length; i++) {
    var interfaceName = arguments[i];
    var interfaceFound = false;

    for (var j = 0; j < object.implementsInterfaces.length; j++) {
      if (object.implementsInterfaces[j] == interfaceName) {
        interfaceFound = true;
        break;
      }
    }
    if (!intefaceFound) {
      return false;
    }
  }
  return true;
}

var CompositeForm = function(id, method, action) {
  this.implementsInterfaces = ['Composite'];
  // ...
};

function addForm(formInstance) {
  if (implements(formInstance, 'composite')) {
    throw new Error(Object does not implement a required interface.);
  }
  // ...
}

// 3. 使用鸭式辨型模仿接口
// 
// 如果对象具有与接口定义的方法同名的所有方法，那么就可以认为它实现了这个接口。
// 使用这种方法需要一个辅助函数来对实现接口的方法进行判断，看某个对象是否实现了某个接口。

// 4. Interface辅助类
// 
// 使用一个辅助类Interface及其类方法Interface.ensureImplements来对对象实现的方法进行显式检查。
var Interface = function(name, methods) {
  if (arguments.length != 2) {
    throw new Error("Interface constructor called with " + arguments.length +
      "arguments, but excepted exactly 2.");
  }

  this.name = name;
  this.methods = [];
  for (var i = 0, len = methods.length; i < len; i++) {
    if (typeof methods[i] !== 'string') {
      throw new Error("interface constructor expects method names to be passed in as a string.");
    }
    this.methods.push(methods[i]);
  }
};

Interface.ensureImplements = function(object) {
  if (arguments.length < 2) {
    throw new Error("Function Interface.ensureImplements expects arguments two and above to be instances of Interface.");
  }

  for (var j = 0, methodsLen = interface.methods.length; j < methodsLen; j++) {
    var method = interface.methods[j];

    if (!object[method] || typeof object[method] !== 'function') {
      throw new Error("Function Interface.ensureImplements: object does not implement the " +
        interface.name + "interface. Method" + method + "was not found.");
    }
  }
}

// 使用

var ResultSet = new Interface('ResultSet',['getDate','getResults']);
var ResultFormatter = function(resultsObject){
  Interface.ensureImplements(resultsObject, ResultSet);
  this.resultsObject = resultsObject;
};
ResultFormatter.prototype.rederResults = function(){
  // ...
};