由于项目需要，在网上找了一个JS判断上传文件大小的程序，经测试兼容IE6-9，Firefox10,Opera11.6,safari5.1,chrome17 <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /> <title>js判断上传文件的大小</title> <script type="text/javascript"> var isIE = /msie/i.test(navigator.userAgent) && !window.opera; var sizeLabel = ["B", "KB", "MB", "GB"]; function fileChange(target) { var fileSize = 0; if (isIE && !target.files) { var filePath = target.value; var fileSystem = new ActiveXObject("Scripting.FileSystemObject"); var file = fileSystem.GetFile (filePath); fileSize = file.Size; } else { fileSize = target.files[0].size; } displayFileSize(fileSize); } function displayFileSize(size) { var fileSize = document.getElementById("fileSize"); fileSize.innerHTML = calFileSize(size); } function calFileSize(size) { for (var index = 0; index < sizeLabel.length; index++) { if (size < 1024) { return round(size, 2) + sizeLabel[index]; } size = size / 1024; } return round(size, 2) + sizeLabel[index]; } function round(number, count) { return Math.round(number * Math.pow(10, count)) / Math.pow(10, count); } </script> </head> <body> <div> <input type="file" onchange="fileChange(this);"> </div> <div id="fileSize"> </div> </body> </html>