| <!DOCTYPE html> |
| <title>Nested top-constrainted position:sticky elements should render correctly</title> |
| <link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" /> |
| <meta name="assert" content="This test checks that nested position:sticky elements with a top constraint render correctly" /> |
| |
| <script src="/resources/testharness.js"></script> |
| <script src="/resources/testharnessreport.js"></script> |
| |
| <script src="../resources/sticky-util.js"></script> |
| |
| <body></body> |
| |
| <script> |
| test(() => { |
| const elements = setupNestedStickyTest('top', 50, 60); |
| elements.scroller.scrollTop = 100; |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY); |
| // The inner sticky should not be offset from the outer. |
| assert_equals(elements.innerSticky.offsetTop, 0); |
| }, 'before reaching the sticking point, neither sticky box should be offset'); |
| |
| test(() => { |
| const elements = setupNestedStickyTest('top', 50, 60); |
| elements.scroller.scrollTop = 145; |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY); |
| assert_equals(elements.innerSticky.offsetTop, 5); |
| }, 'the inner sticky can stick before the outer one if necessary'); |
| |
| test(() => { |
| const elements = setupNestedStickyTest('top', 50, 60); |
| elements.scroller.scrollTop = 200; |
| |
| // This math cancels to sticky.offsetTop == (scroller.scrollTop + 50), but |
| // for clarity the calculations are left explicit. |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| const targetTopY = elements.scroller.scrollTop + 50; |
| const stickyOffset = targetTopY - nonStickyTopY; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY + stickyOffset); |
| |
| // The inner sticky has similar math, but its offsetTop is relative to the |
| // sticky element and in this test is the difference between the top values. |
| assert_equals(elements.innerSticky.offsetTop, 10); |
| }, 'both sticky boxes can be stuck at the same time'); |
| |
| test(() => { |
| const elements = setupNestedStickyTest('top', 50, 60); |
| elements.scroller.scrollTop = 300; |
| const maxOffsetInContainer = elements.container.offsetTop + |
| elements.container.clientHeight - elements.sticky.clientHeight; |
| assert_equals(elements.sticky.offsetTop, maxOffsetInContainer); |
| const maxOffsetInOuterSticky = elements.sticky.clientHeight - |
| elements.innerSticky.clientHeight; |
| assert_equals(elements.innerSticky.offsetTop, maxOffsetInOuterSticky); |
| }, 'neither sticky can escape their containing block'); |
| |
| test(() => { |
| const elements = setupNestedStickyTest('top', 50, 300); |
| elements.scroller.scrollTop = 100; |
| // The outer sticky has not stuck yet. |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY); |
| // But the inner sticky still cannot escape the outer sticky (as it is the |
| // containing block). |
| const maxOffsetInOuterSticky = elements.sticky.clientHeight - |
| elements.innerSticky.clientHeight; |
| assert_equals(elements.innerSticky.offsetTop, maxOffsetInOuterSticky); |
| }, 'the inner sticky cannot be pushed outside the outer sticky'); |
| </script> |
