XMLHttpRequest Origin null is not allowed Access-Control-Allow-Origin for file:/// to file:/// (Serverless)

For instances where running a local webserver is not an option, you can allow Chrome access to file:// files via a browser switch. After some digging, I found this discussion, which mentions a browser switch in opening post. Run your Chrome instance with:

chrome.exe --allow-file-access-from-files

This may be acceptable for development environments, but little else. You certainly don't want this on all the time. This still appears to be an open issue (as of Jan 2011).

See also: Problems with jQuery getJSON using local files in Chrome

Essentially the only way to deal with this is to have a webserver running on localhost and to serve them from there.

It is insecure for a browser to allow an ajax request to access any file on your computer, therefore most browsers seem to treat "file://" requests as having no origin for the purpose of "Same Origin Policy"

Starting a webserver can be as trivial as cding into the directory the files are in and running:

python -m http.server

[Edit Thanks @alextercete, for pointing out that it has updated in Python3]

This solution will allow you to load a local script using jQuery.getScript(). This is a global setting but you can also set the crossDomain option on a per-request basis.

$.ajaxPrefilter( "json script", function( options ) {
  options.crossDomain = true;
});

What about using the javascript FileReader function to open the local file, ie:

<input type="file" name="filename" id="filename">
<script>
$("#filename").change(function (e) {
  if (e.target.files != undefined) {
    var reader = new FileReader();
    reader.onload = function (e) {
        // Get all the contents in the file
        var data = e.target.result; 
        // other stuffss................            
    };
    reader.readAsText(e.target.files.item(0));
  }
});
</script>

Now Click Choose file button and browse to the file file:///C:/path/to/XSL%20Website/data/home.xml

Here is an applescript that will launch Chrome with the --allow-file-access-from-files switch turned on, for OSX/Chrome devs out there:

set chromePath to POSIX path of "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome"    
set switch to " --allow-file-access-from-files"
do shell script (quoted form of chromePath) & switch & " > /dev/null 2>&1 &"

Launch chrome like so to bypass this restriction: open -a "/Applications/Google Chrome.app/Contents/MacOS/Google Chrome" --args --allow-file-access-from-files.

Derived from Josh Lee's comment but I needed to specify the full path to Google Chrome so as to avoid having Google Chrome opening from my Windows partition (in Parallels).

The way I just worked around this is not to use XMLHTTPRequest at all, but include the data needed in a separate javascript file instead. (In my case I needed a binary SQLite blob to use with https://github.com/kripken/sql.js/)

I created a file called base64_data.js (and used btoa() to convert the data that I needed and insert it into a <div> so I could copy it).

var base64_data = "U1FMaXRlIGZvcm1hdCAzAAQA ...<snip lots of data> AhEHwA==";

and then included the data in the html like normal javascript:

<div id="test"></div>

<script src="base64_data.js"></script>
<script>
    data = atob(base64_data);
    var sqldb = new SQL.Database(data);
    // Database test code from the sql.js project
    var test = sqldb.exec("SELECT * FROM Genre");
    document.getElementById("test").textContent = JSON.stringify(test);
</script>

I imagine it would be trivial to modify this to read JSON, maybe even XML; I'll leave that as an exercise for the reader ;)

You can try putting 'Access-Control-Allow-Origin':'*' in response.writeHead(, {[here]}).

use the 'web server for chrome app'. (you actually have it on your pc, wether you know or not. just search it in cortana!). open it and click 'choose file' choose the folder with your file in it. do not actually select your file. select your files folder then click on the link(s) under the 'choose folder' button.

if it doesnt take you to the file, then add the name of the file to the urs. like this:

   https://127.0.0.1:8887/fileName.txt

link to web server for chrome: click me

If you only need to access the files locally then you can include the exact path to the file, rather than using

../images/img.jpg

use

C:/Users/username/directoryToImg/img.jpg

The reason CORS is happening is because you are trying to traverse to another directory within a webpage, by including the direct path you are not changing directory, you are pulling from a direct location.