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