javaScript常用的方法代码

-----------------------------------------接口-----------------------------------------

var Interface = function(name, methods) {
    if(arguments.length != 2) {
        throw new Error("Interface constructor called with " + arguments.length
          + "arguments, but expected 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 called with " +
          arguments.length  + "arguments, but expected at least 2.");
    }

    for(var i = 1, len = arguments.length; i < len; i++) {
        var interface = arguments[i];
        if(interface.constructor !== Interface) {
            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.");
            }
        }
    }
};

-----------------------------------------继承之一类式继承-----------------------------------------

1.function Author(name, books) {
  Person.call(this, name); // Call the superclass' constructor in the scope of this.
  this.books = books; // Add an attribute to Author.
}

Author.prototype = new Person(); // Set up the prototype chain.
Author.prototype.constructor = Author; // Set the constructor attribute to Author.
Author.prototype.getBooks = function() { // Add a method to Author.
  return this.books;
};

var author = [];
author[0] = new Author('Dustin Diaz', ['JavaScript Design Patterns']);
author[1] = new Author('Ross Harmes', ['JavaScript Design Patterns']);

author[1].getName();
author[1].getBooks();

2.function extend(subClass, superClass) {
  var F = function() {};
  F.prototype = superClass.prototype;
  subClass.prototype = new F();
  subClass.prototype.constructor = subClass;
}

3.function extend(subClass, superClass) {
  var F = function() {};
  F.prototype = superClass.prototype;
  subClass.prototype = new F();
  subClass.prototype.constructor = subClass;

  subClass.superclass = superClass.prototype;
  if(superClass.prototype.constructor == Object.prototype.constructor) {
    superClass.prototype.constructor = superClass;
  }
}

-----------------------------------------继承之二原型继承-----------------------------------------

function clone(object) {
    function F() {}
    F.prototype = object;
    return new F;
}

-----------------------------------------继承之三掺元类-----------------------------------------

1.function augment(receivingClass, givingClass) {
  if(arguments[2]) { // Only give certain methods.
    for(var i = 2, len = arguments.length; i < len; i++) {
      receivingClass.prototype[arguments[i]] = givingClass.prototype[arguments[i]];
    }
  } 
  else { // Give all methods.
    for(methodName in givingClass.prototype) { 
      if(!receivingClass.prototype[methodName]) {
        receivingClass.prototype[methodName] = givingClass.prototype[methodName];
      }
    }
  }
}

2.function augment(receivingClass, givingClass) {
  for(methodName in givingClass.prototype) { 
    if(!receivingClass.prototype[methodName]) {
      receivingClass.prototype[methodName] = givingClass.prototype[methodName];
    }
  }
}

-----------------------------------------单体模式-----------------------------------------

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.');
      }
    }
  }

})();

-----------------------------------------工厂方法-----------------------------------------

var SimpleHandler = function() {}; // implements AjaxHandler
SimpleHandler.prototype = {
  request: function(method, url, callback, postVars) {
    var xhr = this.createXhrObject();
    xhr.onreadystatechange = function() {
      if(xhr.readyState !== 4) return;
      (xhr.status === 200) ? 
        callback.success(xhr.responseText, xhr.responseXML) : 
        callback.failure(xhr.status);
    };
    xhr.open(method, url, true);
    if(method !== 'POST') postVars = null;
    xhr.send(postVars);
  },
  createXhrObject: function() { // Factory method.
    var methods = [
      function() { return new XMLHttpRequest(); },
      function() { return new ActiveXObject('Msxml2.XMLHTTP'); },
      function() { return new ActiveXObject('Microsoft.XMLHTTP'); }
    ];
    
    for(var i = 0, len = methods.length; i < len; i++) {
      try {
        methods[i]();
      }
      catch(e) {
        continue;
      }
      // If we reach this point, method[i] worked.
      this.createXhrObject = methods[i]; // Memoize the method.
      return methods[i];
    }
    
    // If we reach this point, none of the methods worked.
    throw new Error('SimpleHandler: Could not create an XHR object.');
  } 
};