AJAX-----10iframe模拟ajax文件上传效果原理2

在实际开发中其实我们可以给用户一些提示，比如上传成功或者上传失败，废话不多说，走码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
    <script src="jq183.js"></script>
    <script>
        function ajaxup(){
            var ifname = 'up'+Math.random();
            $("<iframe name='"+ ifname +"' height='0' width='0' frameborder='0' ></iframe>").appendTo($('body'));
            $('form:first').attr('target',ifname);
            //return false;
        }
    </script>
</head>
<body>
    <p id="mess"></p>
    <form action="9.php" method="post" enctype="multipart/form-data" onsubmit="return ajaxup();">
        <input type="file" name="pic"> <br> <br>
        <input type="submit" value="GO">
    </form>
    <iframe src="" frameborder="0"></iframe>
</body>
</html>

<?php
    if(empty($_FILES)){
        exit('No file');
    }

    $errs = $_FILES['pic']['error'] == 0 ? 'success':'error';
    echo "<script> parent.document.getElementById('mess').innerHTML = '$errs' </script>";