| <!DOCTYPE html> |
| <head> |
| <title>Iframes with loading='lazy' load when in the viewport</title> |
| <link rel="author" title="Scott Little" href="mailto:sclittle@chromium.org"> |
| <link rel="help" href="https://github.com/scott-little/lazyload"> |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| </head> |
| |
| <!-- |
| Marked as tentative until https://github.com/whatwg/html/pull/3752 is landed. |
| --> |
| |
| <script> |
| const t = async_test("Test that iframes with loading='lazy' load once they enter the viewport."); |
| |
| let has_window_loaded = false; |
| let has_in_viewport_loaded = false; |
| |
| const in_viewport_iframe_onload = t.step_func(function() { |
| assert_false(has_in_viewport_loaded, "The in_viewport element should load only once."); |
| has_in_viewport_loaded = true; |
| }); |
| |
| window.addEventListener("load", t.step_func(function() { |
| assert_true(has_in_viewport_loaded, "The in_viewport element should have loaded before window.load()."); |
| assert_false(has_window_loaded, "The window.load() event should only fire once."); |
| has_window_loaded = true; |
| document.getElementById("below_viewport").scrollIntoView(); |
| })); |
| |
| const below_viewport_iframe_onload = t.step_func_done(function() { |
| assert_true(has_window_loaded, "The window.load() event should have fired before below_viewport loaded."); |
| }); |
| </script> |
| |
| <body> |
| <iframe id="in_viewport" src="resources/subframe.html?first" loading="lazy" width="200px" height="100px" onload="in_viewport_iframe_onload();"> |
| </iframe> |
| <div style="height:10000px;"></div> |
| <iframe id="below_viewport" src="resources/subframe.html?second" loading="lazy" width="200px" height="100px" onload="below_viewport_iframe_onload();"> |
| </iframe> |
| |
| <!-- |
| This async script loads very slowly in order to ensure that, if the |
| below_viewport element has started loading, it has a chance to finish |
| loading before window.load() happens, so that the test will dependably fail |
| in that case instead of potentially passing depending on how long different |
| resource fetches take. |
| --> |
| <script async src="/common/slow.py"></script> |
| </body> |
