<!DOCTYPE>
<html>
<head>
<meta http-equiv="Content-type" content="text/html" charset="utf-8">
<title>check file</title>
</head>
<body>
<b>文件扩展名验证</b>
<input type="text" name="int" value="文件.php" onblur="check(this)" id="int">
<input type="button" value="检测" onclick="check_value()">
<script> function check(obj){
if(obj.value == "" || obj.value.length<3){
alert("输入的长度不能小于3且不能为空!");
obj.focus();
}
} function check_value(){ var str = $("int").value; var repx = /\.(php|asp|jsp)$/i; var type = str.substring(str.lastIndexOf("."),str.length); if(type.match(repx) && str.lastIndexOf(".") != -1){
alert("文件扩展名正确");
$("int").focus();
}else{
alert("文件扩展名有误");
$("int").focus();
}
} function $(obj){ return document.getElementById(obj);
}</script>
</body>
</html>
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