jQuery.extend()的用法

 // merge two object, modifying the first;

var object1={

apple:0,

banana:{weight:14,price:233},

cherry:97

};

var object2={

banana:{price:333},

cherry:38

};

jquery.extend(object1,object2);

//result:
 
object1={apple:0,banana{price:333},cherry:38}

//Example: Merge two objects recursively, modifying the first

  var object1 = {

    apple: 0,

    banana: {weight: 52, price: 100},

    cherry: 97

  };

   var object2 = {

    banana: {price: 200},

    durian: 100

  };
 

 
$.extend(true, object1, object2);

//result:

object1 === {apple: 0, banana: {weight: 52, price: 200}, cherry: 97, duria

//Example: Merge defaults and options, //without modifying the defaults. This is a common plugin development pattern.
 //target的参数要传递一个空对象，因为target的值最后要改变 
 var empty = {};
var defaults = { validate: false, limit: 5, name: "foo" };

var options = { validate: true, name: "bar" };

var settings = $.extend(empty, defaults, options);

//result: settings == { validate: true, limit: 5, name: "bar"     empty == { validate: true, limit: 5, name: "bar"}

 jquery.extend()是编写插件是最常用到的工具函数来处理options； 下面是fancybox插件的来处理options;
 例如： settings=jquery.extend({},$.fn.fancybox.defaults,settings);
  上面的代码target是个空对象，这样把默认设置defaults作为第一个对象，将用户传入的设置setting合并到defaults上，  然后将合并后的结果复制给target并将返回值返回。
  下面一个例子： 
  var defaults = { validate: false, limit: 5, name: "foo" };
  var options = { validate: true, name: "bar" };
  var setting=$.extend(defaults,options);
  上面的代码将defaults作为target的参数，最后和setting的值一样但是defaults的值被改变了，而插件的默认值都是固定，所以使用时注意target的参数的用法。