![]() ![]() It sends a GET request for the image with certain headers. Let's explore how does the browser fetch images and resources. There is a very good article explaining this. Well, first, you should know why do websites use the CORS policy. ![]() So why does Google Chrome throw an error when the url is accessed with a CORS header? Note that the second time we try to load the image - Chrome returns a CORS error instead of a response object. The result should look something like this: Load the image again, but this time add a Access-Control-Allow-Origin: * header.This happens for almost all of the s3-hosted images. It's important to be from a different host, and to not return the Access-Control-Allow-Origin: * header, so we can trigger the CORS check. Chose an image url from a different host that has CORS specifications.Open the console in your browser devtools.I'm going to use Google Chrome to demonstrate it. The most widely used of those are Chromium, Google Chrome and Microsoft Edge. ![]() Open a browser running on the Chromium core.The steps to reproduce the issue are the following: You can see in the network tab, that the first image, called without setting crossOrigin, loaded correctly, and the second image, called with crossOrigin="Anonymous" has an error. Start the console in a random website (for example this one) and run this code in it - you should be able to see the error in the network tab. If you open a Google Chrome/Chromium/Microsoft Edge browser. The error messages stated: Access to image at '$' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. In a recent project of ours, we've encountered an issue when fetching images with CORS headers in JavaScript. compressed The cURL (bash) command that Chrome has generated.Have you ever had to load images in JavaScript using the CORS Header crossOrigin="Anonymous"? H 'cookie: ghost-admin-api-session=MASKED' \ H 'accept: application/json, text/javascript, */* q=0.01' \ H 'content-type: application/json charset=UTF-8' \ cURL (bash)įor Linux users, the separator used to continue the command is different in Bash: curl '' \ compressed The cURL (cmd) command that Chrome has generated. H "cookie: ghost-admin-api-session=MASKED" ^ H "accept: application/json, text/javascript, */* q=0.01" ^ H "content-type: application/json charset=UTF-8" ^ If you're on Windows and using the default terminal, you'll probably want to use this cCURL command. If this header is missing from your Node.js script, chances are you can't contact the API. But one of them is the presence of the cookie header in Node fetch. If you carefully compare between the fetch and Node fetch, you might notice that there is not much difference. Sorry! □ fetch await fetch("", ) The Node fetch command that Chrome has generated. I won't show the PowerShell output, as I'm not a fan of this language. Let's take a look at the code they generated. Screenshot of the Network tab inside Chrome DevTools.īut, did you know that by right-clicking on one of the requests, you can copy it to reproduce it? □ Screenshot of the Copy of options in DevTools.Ĭhromium browsers offer us no less than five ways to a request: If you open Chrome DevTools ( F12), navigate to the Network tab and click on the Fetch/XHR filter, you'll see all requests that use the Fetch API (you may need to refresh the page). In this post, I want to share a little trick that you might want to use if you're playing with some APIs: the Copy as function. □Īfter many unsuccessful attempts (probably too many), I finally managed to delete my account after writing a Fetch request. Since I didn't want to contact their support (they really aren't great) and I really want to delete my account, I started looking at their source code to see if I could find a way around it. □♂️- Benjamin Rancourt February 20, 2022 You know a #web app is scrap when you need to look at the #JavaScript code to delete your account. The website has an obscure bug that prevents the submission of the deletion form. This weekend, I tried to delete an account on a website, but I couldn't. ![]()
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