2. 编写一个简单的 jQuery 插件（模板）

//You need an anonymous function to wrap around your function to avoid conflict
(function($){
  

//method一：
    //Attach this new method to jQuery
    $.fn.extend({
          
        //This is where you write your plugin's name
        pluginname: function() {
  
            //options
      //      var defaults = {
      //          option1: "default_value"
      //      }
             
     //       var options = $.extend(defaults, options);
  
            //a public method
     //       this.methodName: function () {
                //call this method via $.pluginname().methodName();
      //      }
  
            //Iterate over the current set of matched elements
            return this.each(function() {
              
      //          var o = options;
              
                //code to be inserted here
              
            });
        }
    });
      
//pass jQuery to the function,
//So that we will able to use any valid Javascript variable name
//to replace "$" SIGN. But, we'll stick to $ (I like dollar sign: ) )   

//method二：  

$.fn.pluginname=function(){
 return this.each(function() {  });
 
}

 
})(jQuery);

实例：

 <script type="text/javascript">
(function($){
 
$.fn.extend({
  check: function() {
    return this.each(function() { alert(0); });
  },
  uncheck: function() {
    return this.each(function() { alert(1); });
  }
});

$.fn.suggest=function(){
    return this.each(function() { alert(2); }); 
}

})(jQuery);

function check(){
 if($("input").attr("checked")){
 $("input").check();
 }else{
 $("input").uncheck();
 }
 $("input").suggest();
}
  </script>