<head><meta charset="utf-8">
<script type="text/javascript">
function check(){
var index=document.getElementById("username").value
if (/^[A-Z]+$/.test(index)) //a-z
{
alert("true")
}
else {
alert("请输入大写英文字母")
return false
}
}
</script>
</head>
<body>
<input type="button"value="提交" onClick="check()">
<input type ="text" id="username">
</body>
</html>
用下面这个,测试过了绝对好用!<html>
<head>
<script language="JavaScript" type="text/javascript">
function alnum(str) {
var alnum = '0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz-_'
for (var i = 0i <str.lengthi++) {
if (alnum.indexOf (str.charAt(i)) == -1) {
return false
}
}
return true
}
function isalnum(){
var reqWord = document.getElementById("reqWord").value
if(alnum(reqWord) == false){
alert("你输入的不是英文、数字或符号!")
}
return true
}
</script>
</head>
<body>
<input id="reqWord" type="text" value="">
<input type="button" onclick="isalnum()" value="OK">
</body>
</html>
var s = "allenglish"var re = new RegExp("^[a-zA-Z]+$")
//要包含数字的话是 new RegExp("^[a-zA-Z0-9]+$")
if (re.test(s)) {alert("是全英文")}
else {alert("不是全英文")}