<html>
<head>
<title>test</title>
<script type="text/javascript">
String.prototype.trim = function()
{
return this.replace(/(^\s*)|(\s*$)/g, "");
}
function check(){
var str = document.getElementById("test").value;
alert(str.trim());
}
</script>
</head>
<body>
<center>
<input id="test" type="text" />
<input id="but" type="button" value="检验" onclick="check();"/>
</center>
</body>
</html>