Using a semantic names like max-file-size and max-input-size make their usage clear. Simplicity and convenience should prevail. Solutions in JS either use several lines or are code-dependent and error-prone. Caution should be observed with Stackoverflow votes. Even if the solution tend to be the simplest ones, the answerers are less prone to question the standards than it should be done here.
Beyond coding verbosity, the main argument against a max file size attribute is that the verification should be performed on server-side.
However, input types and attributes that constraint input values already exist number min max and step, date, email, etc. Any non beginner developer would perform the check on both client and server sides, no matter the type of input. Moreover, a lack of coding a client-side size limit should be counterproductive especially for a file upload if such a limit exists on the server-side.
A too big upload operation should be blocked the sooner as possible and thus preserve the bandwidth we should avoid carrying a fridge to the recycling center if the recycling center won't accept it Skip to content. Star 5. New issue. Jump to bottom. Thus, if your form is meant for submitting plain text files, your best option is probably to ask users to save their text files in UTF-8 encoding with BOM Byte Order Mark. Naturally, this becomes awkward for large files, but it might still be a good idea to have a textarea along with a file input field.
Your server side script would need some more code to handle both. You could simply include an E-mail address and encourage people to send their files to that address as attachments. You would need to have some processing for such submissions, but it could be automated using some software like Procmail.
Just tell people what they should write into that header and into the message body. Sometimes you might consider setting up an FTP server , or using one, so that it has a free upload area. You would then just specify the server and the area, and people could use their favorite FTP clients. Note that for the submission of a large number of files, FTP would be more comfortable than using a form with a file input field.
Especially for local users, you could just give a physical address to which people can bring or send their files e. Make it clear to them in advance which media and formats you can handle that way. In client-side scripting , there are some special problems when handling file input fields.
FAQ How can I extract just the file name from a forms file upload field? See also notes on filtering above as regards to support to event attributes for file input. The HTML 4. The notes below hopefully help in locating and interpreting the relevant portions. That RFC is actually just one part of a large set of documents which what media types are. In particular, the general description of the media type concept is in RFC But in the context of form submission, the use of a media type as the value of the enctype attribute is meaningful only if there is a definition of the conversion to be done.
The definition must be rigorous, since otherwise it is impossible to process the data in a useful, robust way by computer programs. Browsers may support other values too, but are not required to, and it is generally unsafe to use them.
Normally you should not try to re-invent the wheel by writing code which interprets decodes the encoded form data. Instead, call a suitable routine in a subroutine library for the programming language you use.
It typically decodes the data into a convenient format for you to process in your own code. It seems that the HTML 4. But e. IE 4 and Netscape 4 handle form submissions incorrectly if the enctype is defaulted in such a case: they send the name of the file instead of its content! It specifies file select so that this control type allows the user to select files so that their contents may be submitted with a form.
Note that there is nothing an author needs to do, and nothing he can do, to make a browser allow the selection of several files per input field.
It depends on the browser whether that is possible. However, as described above, the current browser support is poor: only some versions of Opera support multi-selection, and these do not include the newest versions. Naturally the server-side script must then be somehow prepared to handle zipped files.
It might be all too easy to lure some users into submitting some password files! It also mentions in section 3. The mechanism for getting the original file name would be quite unreliable for such purposes. A more useful application could be this: Assume that your form is for reporting a problem with a particular program, say Emacs, and that program uses a configuration file with some specific name, say.
Setting the default name, if supported by the browser, might be an extra convenience to the user. Thus, they just failed to implement it , for no good reason. The situations where it would make sense to suggest a default file name are rare. Unlike other controls, this value is read-only. And in fact, one can read the value in JavaScript and get the filename entered by the user but setting it is unsuccessful without an error message ; the same applies to Netscape but on Opera, even an attempt to read the value seems to confuse the browser.
However, support to file input in several versions of Opera handles the value attribute in the following way: the value is displayed in the box for file name input that value can be edited by the user as an alternative to using the Browse menu, which changes the content of that box however if the user submits the form so that the initial value has not been changed by the user, there will be a security alert and the user is requested to confirm the submission.
Such support, however, is absent in Opera 7. Your browser probably just ignores that attribute, but some browsers may use it to set the initial file name:. This is a convenience for those cases where, for example, the uploaded files might contain references to each other, e. But note that this appears in subsection 3. Suggested Implementatation. Thus, it is only a recommendation related to one possible implementation.
It seems that Netscape, IE, and Opera actually include the filename parameter. However, only Opera uses the format which seems to be the intended one, as deduced from the examples in RFC section 6 , namely a relative name like foo. Internet Explorer 7 beta preview behaves similarly, and this has been explained as a security improvement. Is the Netscape and IE behavior really incorrect? Well, since most computers have some sort of path name system for file names, one would expect to see path names in examples if the intent had been that path names are sent.
Note that the security section of RFC does not mention any problems that might arise from that; this more or less proves that browsers were not expected to send path names.
The idea of including a filename attribute makes sense of course, and would apply e. Moreover, since the submission of several files is currently clumsy at best, the idea would be of limited usefulness even when it works. Although the user is not expected to type the filename s into a filename box but use the Browse function, the size of the box matters.
When the user selects a file by clicking on it, the browser puts the filename into the filename box, and the name is a full pathname which can be quite long. It may confuse users if they see the name badly truncated. And most browsers seem to treat the size attribute that way. But the HTML 4. The width is given in pixels except when type attribute has the value "text" or "password".
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