jquery通过扩展select控件实现支持enter或focus选择的方法

/**************************************** @ author jdkleo* @ date 2013/2/27 JQuery SelKeysUSAGE: jQuery.selkeys.enter(jQuery("#selcon")); jQuery.selkeys.focus(jQuery("#selcon2"));*****************************************/(function (jQuery){ this.version = '(beta)(0.0.1)'; this.all = {}; /**---------enter---------**/ this.enter = function(sel){   var flag = 1;  var open = function(){    if(flag==1){    sel.get(0).size = sel.get(0).options.length;    flag=0;   }else{    sel.get(0).size = 1;    flag=1;   }  };   sel.keydown(function(e){     e = e ? e :(window.event ? window.event : null);     var code = e.keyCode || e.which || e.charCode;    if(code == 13)    {     open();     return false;    }   });  sel.blur(function(){     sel.get(0).size=1;     flag=1;     });    }  /**---------focus---------**/ this.focus = function(sel){   var flag = 1;  var open = function(){    if(flag==1){    sel.get(0).size = sel.get(0).options.length;    flag=0;   }else{    sel.get(0).size = 1;    flag=1;   }  };   sel.focus(function(){     open();    return false;   });  sel.blur(function(){    sel.get(0).size=1;    flag=1;   });  sel.keydown(function(e){     e = e ? e :(window.event ? window.event : null);     var code = e.keyCode || e.which || e.charCode;    if(code == 13)    {     sel.get(0).size=1;     flag=1;     return false;    }   }); } /**---------all---------**/ jQuery.selkeys = this; return jQuery; })(jQuery);