how validate file size using HTML and Javascript on client side

How can I validate the file size on the client side using JavaScript? I am using type=file for selecting the file


Solution 1:

UPDATE 2013 as of this edit, the File API is supported in all major browsers, and in IE as of version 10

http://caniuse.com/#search=file%20api

You may still wish to use SWFUpload if you still need to support IE9 and under, though at this point it should probably be more of a fallback, since the html5 file api has support on mobile platforms where SWFUpload cannot reach. The html5 file api is based on firefox's file api as noted below.

See also this duplicate question Client Checking file size using HTML5?

UPDATE: Firefox has changed their API to this https://developer.mozilla.org/en/DOM/FileReader

You can do it in firefox like so

html:

<form action="" method="get" accept-charset="utf-8">
<input type="file" name="file" value="" id="file">
<p><input type="submit" value="Continue &rarr;"></p>
</form>

javascript:

var filesize = document.forms[0].file.files[0].fileSize

if there's a way to do this in IE, I don't know it. It probably involves activeX or some other such rubbish.

edit: I found this here, HOW TO DO THIS IN IE

<head>
<script>
function getSize()
{
 var myFSO = new ActiveXObject("Scripting.FileSystemObject");
 var filepath = document.upload.file.value;
 var thefile = myFSO.getFile(filepath);
 var size = thefile.size;
 alert(size + " bytes");
}
</script>
</head>
<body>
<form name="upload">
<input type="file" name="file">
<input type="button" value="Size?" onClick="getSize();">
</form>
</body>
</html>

Solution 2:

Perhaps you could use SWFUpload instead, which is a small Flash application that handles the client side of the upload for you. From their feature list:

  • Upload multiple files at once by ctrl/shift-selecting in dialog
  • Javascript callbacks on all events
  • Get file information before upload starts
  • Style upload elements with XHTML and css
  • Display information while files are uploading using HTML
  • No page reloads necessary
  • Works on all platforms/browsers that has Flash support.
  • Degrades gracefully to normal HTML upload form if Flash or javascript is unavailable
  • Control filesize before upload starts
  • Only display chosen filetypes in dialog
  • Queue uploads, remove/add files before starting upload