本文实例讲述了javascript实现校验文件上传控件。分享给大家供大家参考。具体如下：

该javascript校验文件上传控件代码可检测上传文件的类型是否是图片

<script language="javascript"> function Checkfiles() { var fup = document.getElementById('logo1'); var fileName = fup.value; var ext = fileName.substring(fileName.lastIndexOf('.') + 1); if(ext == "gif" || ext == "GIF" || ext == "JPEG" || ext == "jpeg" || ext == "jpg" || ext == "JPG" || ext == "png" || ext == "PNG") { return true; } else { alert("Upload JPG, JPEG, PNG, GIF images only"); fup.focus(); return false; } } </script> onchange="Checkfiles()"

希望本文所述对大家的javascript程序设计有所帮助。