Gilles Dubuc 28b8f5095e Use cross-origin img attribute instead of data URI ... After lots of experimenting with Wireshark and current Chrome + Firefox on Ubuntu 13.10, this is my current understanding of the caching when preloading images with AJAX requests: * on Chrome, the image request always comes from browser cache * Firefox makes two separate requests by default * Firefox with img.crossOrigin = 'anonymous' makes two separate requests, but the second one is a 304 (does not load the image twice) * when the image has already been cached by the browser (but not in this session), Chrome skips both requests; Firefox skips the AJAX request, but sends the normal one, and it returns with 304. "wish I knew this when I started" things: * the Chrome DevTools has an option to disable cache. When this is enabled, requests in the same document context still come from cache (so if I load the page, fire an AJAX request, then without reloading the page, fire an AJAX request to the same URL, then the second request will be cached), but an AJAX request - image request pair is an exception from this. * when using Ctrl-F5 in Firefox, requests on that page will never hit the cache (even AJAX request fired after user activity; even if two identical requests follow each other). When using clear cache + normal reload, this is not the case. * if the image does not have an Allow-Origin header and is loaded with crossOrigin=true, Firefox will refuse to load it. Chrome will log an error in the console saying it refused to load it, but will actually load it. * Wireshark rocks. Pushed some tech debt (browser + domain whitelist) into other tickets: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/232 https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/233 Reverted commits: 8a8d74f01d. 63021d0b0e. Change-Id: I84ab2f3ac0a9706926adf7fe8726ecd9e9f843e0 Bug: 61542 Mingle: https://wikimedia.mingle.thoughtworks.com/projects/multimedia/cards/207		2014-02-24 07:56:40 +00:00
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basic_mmv_navigation_steps.rb	Use cross-origin img attribute instead of data URI	2014-02-24 07:56:40 +00:00