Do You Really Know CORS?
This is an awesome overview! But don't take it as all encompassing, it doesn't go into some of the more esoteric edge cases with CORS, like:* either an unreleased safari version, or the most recent version will send preflight requests even if the request meets the spec (like if the Accept-Language is set to something they don't like).* If you use the ReadableStream API with fetch in the browser, a preflight will be sent.* If there are any events attached on the XMLHttpRequestUpload.upload listener, it will cause a preflight* cross-domain @font-face urls, images drawn to a canvas using the drawImage stuff, and some webGL things will also obey CORS* the crossorigin attribute will be required for cross-origin linked images or css, or the response will be opaque and js won't have access to anything about it.* if you mess up CORS stuff, you get opaque responses, and opaque responses are "viral", so they can cause entire canvas elements to become "blacklisted" and extremely restricted.I feel like I've cut my teeth on this API more than most, and I still feel like I'm only scratching the surface!