CORS request fails when sending empty string for data

[pamelafox]

If I specify an empty string for data in an AJAX request, the request fails due to CORS error ("not allowed by Access-Control-Allow-Origin."). It works fine with jQuery $.ajax and works fine if I pass in null instead. Perhaps it's a mistake to pass in an empty string, I'm not sure, but it took some debugging to figure out why it wasn't working.

Code:

    $.ajax({
        url: url,
        type: 'POST',
        data: '',
        dataType: 'json',
        xhrFields: {
          withCredentials: true
        },
        success: function(responseJSON, textStatus, xhr) {
        },
        error: function(xhr, textStatus, errorThrown) {
        }
     });

[mislav]

Interesting. Maybe we should turn empty string into null internally to work around this.

Thanks for the report, and all the contributions you've made! Seriously awesome 👍 👍

[pamelafox]

Yeah I added a line that turns empty string into null in my zepto.js, and that works.

I should clarify that it fails in Chrome - this could well be a browser-specific issue. CORS issues often are.

[ashok-v]

@pamelafox can you share the fix that is working for you

TIA

[pamelafox]

I added the check for empty string right before the call to xhr.send:

if (settings.data === '') settings.data = null;
xhr.send(settings.data);