Find the source of an XMLHttpRequest using Chrome/Firefox dev tools
It turns out – yes, there is. That “XHR Breakpoints” option on the side which I had always ignored: It works perfectly. Firefox has an identical feature:
xmlhttprequest
Ajax – 500 Internal Server Error
The 500 (internal server error) means something went wrong on the server’s side. It could be several things, but I would start by verifying that the URL and parameters are correct. Also, make sure that whatever handles the request is expecting the request as a GET and not a POST. One useful way to learn … Read more
How to set access-control-allow-origin in webrick under rails?
Rails 4 (http://edgeguides.rubyonrails.org/security.html#default-headers) In config/application.rb: config.action_dispatch.default_headers.merge!({ ‘Access-Control-Allow-Origin’ => ‘*’, ‘Access-Control-Request-Method’ => ‘*’ })
Uploading File in parts using XMLHttpRequest and auth digest
I have a couple ideas. What happens if you wait for the blob slice to be created before making the upload call? const firstBlob = await new Promise(resolve => { newBlob.slice(0, 262144).onCreated(resolve) }); // send request with blob firstBlob.safeClose(); const secondBlob = await new Promise(resolve => { newBlob.slice(262144, 262144 * 2).onCreated(resolve) }); // etc It … Read more
JavaScript Blob Upload with FormData
You have a typo in the function uploadCanvasData it should read formData.append(“file”, blob); Read your code more carefully!
How to tell if an XMLHTTPRequest hit the browser cache
From the XMLHttpRequest spec: For 304 Not Modified responses that are a result of a user agent generated conditional request the user agent must act as if the server gave a 200 OK response with the appropriate content. In other words, the browser will always give status code 200 OK, even for requests that hit … Read more
How to make cross domain request [duplicate]
You can make cross domain requests using the XMLHttpRequest object. This is done using something called “Cross Origin Resource Sharing”. See: http://en.wikipedia.org/wiki/Cross-origin_resource_sharing Very simply put, when the request is made to the server the server can respond with a Access-Control-Allow-Origin header which will either allow or deny the request. The browser needs to check this … Read more
Empty responseText from XMLHttpRequest
Is http://api.xxx.com/ part of your domain? If not, you are being blocked by the same origin policy. You may want to check out the following Stack Overflow post for a few possible workarounds: Ways to circumvent the same-origin policy
How to make XMLHttpRequest cross-domain withCredentials, HTTP Authorization (CORS)?
I’ve written an article with a complete CORS setup. I found several issues that can result in this problem: The Access-Control-Allow-Origin cannot be a wildcard if credentials are being used. It’s easiest just to copy the Origin header of the request to this field. It’s entirely unclear why the standard would disallow a wildcard. Firefox … Read more
Chrome DevTools: jump from XHR network request, to the code that made it
See the “Initiator” column in the network tab. It tells you which code initiated the AJAX call. You will also get a tooltip with a full stack trace.