Wikipedia:Reference desk/Archives/Computing/2018 June 24

= June 24 =

Javascript file upload prevention
I know that in a website that uses Javascript, I can navigate to a file and upload it. But what prevents the Javascript from uploading a file without my knowledge? Jc3s5h (talk) 11:18, 24 June 2018 (UTC)
 * Javascript generally does not have access to the local file system. So, there is nothing to fear here. Ruslik_ Zero 20:47, 24 June 2018 (UTC)
 * A website doesn't have to use JavaScript to implement file upload. A website using plain HTML can also upload a file. But whether it uses JavaScript or not, a file cannot be uploaded unless you manually select one. CodeTalker (talk) 11:36, 25 June 2018 (UTC)


 * Currently (2018), the file tag can be set with JavaScript. Once set, it can be submitted using Ajax without notifying you. So, it is possible that a web browser can submit a local file without notifying you. The security fix is that JavaScript is limited in how it can set the file tag. It can only set it using a file list, which is only created by the user selecting a file. So, you cannot set the file tag's value without an action by the user. So, the goal is trick users into selecting files without the user realizing he or she is selecting a file. It isn't a case of JavaScript uploading files without your knowledge. It is a case of JavaScript uploading files without your understanding. 209.149.113.5 (talk) 13:46, 25 June 2018 (UTC)

up-arrow and down-arrow keys
I have a two-year-old Lenovo Thinkpad. At the lower right corer of the keyboard are the left arrow, to the right of that the down arrow, to the right of that the right arrow, and just above the down arrow the up arrow. Today the up arrow and down arrow are behaving differently from the way they have in the past. In Facebook status postings they don't work at all. In a plain text file viewed with Notepad they cause the cursor to move normally upward and downward, but if the cursor is on the lowest line, formerly the down arrow cause it to move to the end of the line, and that's not happening today. Similarly the up arrow on the top line moved the cursor to the beginning, and that's not happening. On this present Wikipedia editing page, both arrows are functioning normally. I restarted the machine a few minutes ago and the problem persists.

What's going on and what should I do about it? Michael Hardy (talk) 18:41, 24 June 2018 (UTC)
 * Could you have accidentally turned scroll-lock on? ApLundell (talk) 23:11, 25 June 2018 (UTC)
 * Is the Notepad thing even standard behaviour with Notepad? I'm not sure it is. If you are selecting than then it will have that end of line behaviour. If you are simply moving the cursor, I'm not so sure. (I'm sure I've observed it before, but I can't recall for sure.) I tried with Notepad, Wordpad and Word 2017 on Windows 10, none of them have the behaviour. Chrome and Firefox edit windows on wikipedia do, as does Notepad++. Internet Explorer and Edge edit Windows windows of wikipedia have an intermediate. Trying to move the cursor with the down arrow key on the last line does scroll to the end of the line. However doing the same with the up arrow key on the first line does not. See also this discussion where a change for this behaviour was limited to OS X because it was not shown on Qt, or LibreOffice even on OS X, Microsoft Office or Internet Explorer [//musescore.org/en/node/268197] [//github.com/musescore/MuseScore/pull/3382]. On the last point, I wonder if this means IE has changed or it's depends on the text field or the person only tested the up direction and just assumed it was the same. Nil Einne (talk) 10:58, 26 June 2018 (UTC)


 * Facebook broke a couple of days ago. Several people have had the same problem. Andy Dingley (talk) 11:59, 26 June 2018 (UTC)

Windows 10 and (no) sound.
I have Dell OPtiplex 755. Since Windows kindly updated to version 10, I have had no sound. Ive tried changing drivers, but Device manager will not allow me to roll back. I tried searching for new drivers, but it tells me I have up to date drivers. Ive tried uninstalling all audio devices and restarting the compuiter: no joy. Can anyone suggest anything to to get my sound back? 213.205.242.197 (talk) 23:07, 24 June 2018 (UTC)
 * See [//www.dell.com/downloads/global/products/optix/en/opti_755_techspecs.pdf] to start with for info on your computer. Have you tried these drivers ? They are listed as supporting Windows 10 although I don't know if they work on your particular version [//answers.microsoft.com/en-us/windows/forum/windows_10-performance-winpc/no-sound-after-new-version-of-windows-10-updated/66878345-8a37-40ee-b435-8354dbaf2bd9] Nil Einne (talk) 10:30, 25 June 2018 (UTC)


 * You may just need to reboot to get it working. Once this fixed the same problem for me. Another time when I had no sound, I had an mp3 player that had a usb audio output that took over from the regular computer speakers. Unplugging that got the sound back. Graeme Bartlett (talk) 00:07, 27 June 2018 (UTC)