//1.用单双引号拼接 
var valueDemo = "111"; 
var htmlStrs1 = '<option selected="selected" value="'+valueDemo+'"></option>'; 
alert(htmlStrs1); 
//2.通过转义字符拼接 
var htmlStrs2 = "<option selected=\"selected\" value=\""+valueDemo+"\">"+valueDemo+"</option>"; 
alert(htmlStrs2); 
//3.通过Jqquery直接创建标签对象 
$("<option></option>")