Check if file (ClickOnce) exists using jQuery

Question

I am trying to find out whether or not a file exists, before trying to download it. The file is a ClickOnce application.

I have already tried the following code, but this does not work (maybe because the URL is on a different server and domain?);

$.ajax({
    url: 'http://www.example.com/somefile.ext',
    type: 'HEAD',
    error: function()
    {
        //File does not exist
    },
    success: function()
    {
        // File exists
    }
});

Is there another solution, or is there a means to get this one to work?

Call a method on the server that can talk to the IO system instead. — asawyer, Sep 17 '12 at 12:49

score 0 · Accepted Answer · edited May 23 '17 at 12:33

0

Yes, this should not work if the URL is on a different server. If you want to make this work, you will need control over the server where the URL is downloaded from. If so, you should set the Access-Control-Allow-Origin header to the name of the server from which your JavaScript is loaded.

See Stack Overflow question jQuery AJAX cross domain for more details.

edited May 23 '17 at 12:33

Community

1
1

answered Sep 17 '12 at 12:51

Hans Then

10,935
3
32
51

score 0 · Answer 2 · answered Sep 17 '12 at 12:52

0

You cannot make Cross-Domain Calls this easily (CORS). It is better and safer to call a script on your server which checks for the existence of the file and returns an according result.

answered Sep 17 '12 at 12:52

Christoph

50,121
21
99
128

@drbaltar I don't understand you... How do you want to do your ajax request in the first place if you don't know the servername? – Christoph Sep 17 '12 at 15:09

score 0 · Answer 3 · answered Sep 17 '12 at 12:56

Besides what the others have said, you should also check the errorThrown argument to the error function to be "Not Found". Otherwise you may be assuming a file doesn't exist when really a different error occurred.

When an HTTP error occurs, errorThrown receives the textual portion of the HTTP status, such as "Not Found" or "Internal Server Error."

Check if file (ClickOnce) exists using jQuery

3 Answers3