《javascript设计模式》笔记之第五章：单体模式

var Singleton = {
  attribute1: true,
  attribute2: 10,

  method1: function() {

  },
  method2: function(arg) {

  }
};

var GiantCorp = {};

GiantCorp.Common = {
  // A singleton with common methods used by all objects and modules.
};

GiantCorp.ErrorCodes = {
  // An object literal used to store data.
};

GiantCorp.PageHandler = {
  // A singleton with page specific methods and attributes.
};

Namespace.PageName = {

  // Page constants.
  CONSTANT_1: true,
  CONSTANT_2: 10,

  // Page methods.
  method1: function() {

  },
  method2: function() {

  },

  // Initialization method.
  init: function() {

  }
}

addLoadEvent(Namespace.PageName.init);

var formID = document.getElementById("form");
formID.addEventListener(‘submit‘,formSubmit,false);

function formSubmit(e) {
        //阻止表单默认动作，然后用ajax发送数据
        //接受数据之后调用callBack函数
}

function callBack(data) {
        //用ajax提交表单之后的回调函数

var GiantCorp = window.GiantCorp || {};
GiantCorp.RegPage = {
        formID: ‘form‘,
        callBack: function(data) {
                //用ajax提交表单之后的回调函数
        },
        formSubmit: function(e) {
                //阻止表单默认动作，然后用ajax发送数据
                //接受数据之后调用callBack函数
        },
        init: function(e) {
                GiantCorp.RegPage.formEl = document.getElementById(GiantCorp.RegPage.formID);
                GiantCorp.RegPage.formEl.addEventListener(‘submit‘,GiantCorp.RegPage.formSubmit,false);
        }
}

GiantCorp.RegPage.init();

GiantCorp.DataParser = {
  // Private methods.
  _stripWhitespace: function(str) {
    return str.replace(/\s+/, ‘‘);
  },
  _stringSplit: function(str, delimiter) {
    return str.split(delimiter);
  },
  
  // Public method.
  stringToArray: function(str, delimiter, stripWS) {
    if(stripWS) {
      str = this._stripWhitespace(str);
    }
    var outputArray = this._stringSplit(str, delimiter);
    return outputArray;
  }
};

MyNamespace.Singleton = (function() {
  // Private members.
  var privateAttribute1 = false;
  var privateAttribute2 = [1, 2, 3];
  
  function privateMethod1() {
    ...
  }
  function privateMethod2(args) {
    ...
  }

  return { // Public members.
    publicAttribute1: true,
    publicAttribute2: 10,
    
    publicMethod1: function() {
      ...
    },
    publicMethod2: function(args) {
      ...
    }
  };
})();

MyNamespace.Singleton = (function() {

  function constructor() { // All of the normal singleton code goes here.
    // Private members.
    var privateAttribute1 = false;
    var privateAttribute2 = [1, 2, 3];
  
    function privateMethod1() {
      ...
    }
    function privateMethod2(args) {
      ...
    }

    return { // Public members.
      publicAttribute1: true,
      publicAttribute2: 10,
    
      publicMethod1: function() {
        ...
      },
      publicMethod2: function(args) {
        ...
      }
    }
  }
  
})();

MyNamespace.Singleton = (function() {
  
  function constructor() { // All of the normal singleton code goes here.
    ...
  }
  
  return {
    getInstance: function() {
      // Control code goes here.
    }
  }
})();

MyNamespace.Singleton = (function() {
  
  var uniqueInstance; // Private attribute that holds the single instance.
  
  function constructor() { // All of the normal singleton code goes here.
    ...
  }
  
  return {
    getInstance: function() {
      if(!uniqueInstance) { // Instantiate only if the instance doesn‘t exist.
        uniqueInstance = constructor();
      }
      return uniqueInstance;
    }
  }
})();

MyNamespace.Singleton = (function() {
  var objectA = {
    method1: function() {
      ...
    },
    method2: function() {
      ...
    }
  };
  var objectB = {
    method1: function() {
      ...
    },
    method2: function() {
      ...
    }
  };

  return (someCondition) ? objectA : objectB;
})();

/* SimpleXhrFactory singleton, step 1. */

var SimpleXhrFactory = (function() {
  
  // The three branches.
  var standard = {
    createXhrObject: function() {
      return new XMLHttpRequest();
    }
  };
  var activeXNew = {
    createXhrObject: function() {
      return new ActiveXObject(‘Msxml2.XMLHTTP‘);
    }
  };
  var activeXOld = {
    createXhrObject: function() {
      return new ActiveXObject(‘Microsoft.XMLHTTP‘);
    }
  };
  
})();

/* SimpleXhrFactory singleton, step 2. */

var SimpleXhrFactory = (function() {
  
  // The three branches.
  var standard = {
    createXhrObject: function() {
      return new XMLHttpRequest();
    }
  };
  var activeXNew = {
    createXhrObject: function() {
      return new ActiveXObject(‘Msxml2.XMLHTTP‘);
    }
  };
  var activeXOld = {
    createXhrObject: function() {
      return new ActiveXObject(‘Microsoft.XMLHTTP‘);
    }
  };
  
  // To assign the branch, try each method; return whatever doesn‘t fail.
  var testObject;
  try {
    testObject = standard.createXhrObject();
    return standard; // Return this if no error was thrown.
  }
  catch(e) {
    try {
      testObject = activeXNew.createXhrObject();
      return activeXNew; // Return this if no error was thrown.
    }
    catch(e) {
      try {
        testObject = activeXOld.createXhrObject();
        return activeXOld; // Return this if no error was thrown.
      }
      catch(e) {
        throw new Error(‘No XHR object found in this environment.‘);
      }
    }
  }

})();