JS判断文本框内的内容是否为空

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 1 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 2 
 3 <html xmlns="http://www.w3.org/1999/xhtml">
 4 <head>
 5     <title></title>
 6 </head>
 7 <body>
 8     <script type="text/javascript">
 9         function JTrim1(s) {
10             return s.replace(/(^\s*)|(\s*$)/g, "");
11         }
12 
13         function JTrim2(s) {
14             return s.replace(/\s+/g, "");
15         }
16 
17         function validator1() {
18             var var1 = document.getElementById("1");
19             if (JTrim1(var1.value) == "")
20                 alert("对不起，你没有输入内容");
21             else
22                 alert("你输入了内容");
23         }
24 
25         function validator2() {
26             var var1 = document.getElementById("1");
27             if (JTrim2(var1.value) == "")
28                 alert("对不起，你没有输入内容");
29             else
30                 alert("你输入了内容");
31         }       
32     </script> 
33     <input type= "text" id= "1" value=""/> 
34     <br />    
35     <input type="button" name="name" value="vaildator1()" onclick= "validator1();" />
36     <br />       
37     <input type="button" name="name" value="vaildator2()" onclick= "validator2();" />
38     <br />   
39 </body>
40 </html>