Check if a file exists locally using JavaScript only

Question

I want to check if a file exists locally  where the HTML file is located  It has to be JavaScript  JavaScript will never be disabled  jQuery is not good but can do   By the way  I am making a titanium app for Mac so I am looking for a way of protecting my files from people who click  show package contents

User · Answer

You can use this  function LinkCheck url        var http   new XMLHttpRequest        http open  HEAD   url  false       http send        return http status  404

User · Answer

Your question is ambiguous  so there are multiple possible answers depending on what you re really trying to achieve   If you re developping as I m guessing a desktop application using Titanium  then you can use the FileSystem module s getFile to get the file object  then check if it exists using the exists method   Here s an example taken from the Appcelerator website   var homeDir   Titanium Filesystem getUserDirectory    var mySampleFile   Titanium Filesystem getFile homeDir   sample txt     if  mySampleFile exists          alert  A file called sample txt already exists in your home directory                 Check the getFile method reference documentation  And the exists method reference documentation  For those who thought that he was asking about an usual Web development situation  then thse are the two answers I d have given   1  you want to check if a server-side file exists   In this case you can use an ajax request try and get the file and react upon the received answer  Although  be aware that you can only check for files that are exposed by your web server  A better approach would be to write a server-side script  e g   php  that would do the check for you  given a filename and call that script via ajax  Also  be aware that you could very easily create a security hole in your application server if you re not careful enough   2  you want to check if a client-side file exists   In this case  as pointed you by others  it is not allowed for security reasons  although IE allowed this in the past via ActiveX and the Scripting FileSystemObject class  and it s fine like that  nobody wants you to be able to go through their files   so forget about this

User · Answer

If you want to check if file exists using javascript then no  as far as I know  javascript has no access to file system due to security reasons   But as for me it is not clear enough what are you trying to do

User · Answer

Javascript cannot access the filesystem and check for existence  The only interaction with the filesystem is with loading js files and images  png gif etc     Javascript is not the task for this

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Fortunately  it s not possible  for security reasons  to access client-side filesystem with standard JS  Some proprietary solutions exist though  like Microsoft s IE-only ActiveX component

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One way I ve found to do this is to create an img tag and set the src attribute to the file you are looking for   The onload or onerror of the img element will fire based on whether the file exists   You can t load any data using this method  but you can determine if a particular file exists or not

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Try this   window onclick  function      try       var file   window open  file   mnt sdcard download Click ogg        setTimeout  file close     100       setTimeout  alert  Audio file found  Have a nice day       101       catch err        var wantstodl confirm  Warning  n the file  Click ogg is not found  n do you want to download it  n   err message       if  wantstodl          window open  https   www dropbox com s qs9v6g2vru32xoe Click ogg dl 1      downloads the audio file

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An alternative  you can use a  hidden  applet element which implements this exist-check using a privileged action object and override your run method by   File file   new File yourPath   return file exists

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No need for an external library if you use Nodejs all you need to do is import the file system module  feel free to edit the code below      const fs   require  fs    const path      file txt   fs access path  fs F OK   err    gt      if  err        console error err      return          file exists

User · Answer

Since  Kranu  helpfully advises  The only interaction with the filesystem is with loading js files         that suggests doing so with error checking would at least tell you if the file does not exist - which may be sufficient for your purposes   From a local machine  you can check whether a file does not exist  by attempting to load it as an external script then checking for an error   For example    lt span gt File exists   lt  span gt   lt SCRIPT gt      function get error x           document getElementsByTagName  span   0  innerHTML  x   does not exist              url      put your path file name in here            url      new Date   getTime   Math floor Math random   1000000       var el document createElement  script        el id  123       el onerror function   if el onerror get error this id       el src url      document body appendChild el    lt  SCRIPT gt    Some notes       append some random data to the file name  url      new Date etc  so that the browser cache doesn t serve an old result  set a unique element id  el id   if you re using this in a loop  so that the get error function can reference the correct item  setting the onerror  el onerror function  line is a tad complex because one needs it to call the get error function AND pass el id - if just a normal reference to the function  eg  el onerror get error  were set  then no el id parameter could be passed  remember that this only checks if a file does not exist

[javascript] Check if a file exists locally using JavaScript only

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