文本框限制

1<input onkeypress="a()" onpaste="return false" type="text"/>

1<br/>

1<input onkeypress="b()" onpaste="return false" type="text"/>

1<br/>

1<input onkeypress="c()" onpaste="return false" type="text"/>

1<br/>

1<input onkeypress="d()" onpaste="return false" type="text"/>

1<br/>

 1<script language="javascript">   
 2function a()   
 3{   
 4var k = window.event.keyCode;   
 5if (k < 48 ¦ ¦ k > 57){   
 6alert("你输入的不是数字！")   
 7window.event.keyCode = 0 ;}   
 8}   
 9  
10function b()   
11{   
12var k = window.event.keyCode;   
13if (k < 255){   
14alert("你输入的不是汉字！");   
15window.event.keyCode = 0 ;}   
16}   
17  
18function c()   
19{   
20var k = window.event.keyCode;   
21if (k > 255){   
22alert("你输入了汉字！");   
23window.event.keyCode = 0 ;}   
24}   
25  
26function d()   
27{   
28var k = window.event.keyCode;   
29if (!(((k >= 48) && (k <=57)) ¦ ¦ ((k>=65) && (k<=90)) ¦ ¦ ((k>=97) && (k<=122)))){   
30alert("你输入了非法字符！");   
31window.event.keyCode = 0 ;}   
32}   
33</script>