Why Can't I Directly Set the Value of an HTML File Input?

How to Set a Value to a File Input in HTML

Many developers have encountered the challenge of setting a value to a file input in HTML. While this may seem like a straightforward task, it's not possible due to security concerns.

Security Concerns

Allowing a website to set the value of a file input to a client-side disk file system path would pose a significant security risk. Consider the following malicious scenario:

<form name="foo" method="post" enctype="multipart/form-data">
    <input type="file" value="c:/passwords.txt">
</form>
<script>document.foo.submit();</script>

If this malicious code were executed, the website would be able to surreptitiously obtain a copy of the user's sensitive passwords.

Limited Option

While setting a file input value to a specific path is not feasible, there is a limited workaround: setting it to a publicly accessible web resource. However, this option is of little practical use in the context of managing local files on the user's computer.

The above is the detailed content of Why Can't I Directly Set the Value of an HTML File Input?. For more information, please follow other related articles on the PHP Chinese website!