| <!DOCTYPE html> |
| <title>position:sticky elements should respect the bottom constraint</title> |
| <link rel="help" href="https://www.w3.org/TR/css-position-3/#sticky-pos" /> |
| <meta name="assert" content="This test checks that position:sticky elements obey their bottom anchor after scrolling" /> |
| |
| <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 = setupStickyTest('bottom', 25); |
| elements.scroller.scrollTop = 300; |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY); |
| }, 'before reaching the sticking point the sticky box should not be offset'); |
| |
| test(() => { |
| const elements = setupStickyTest('bottom', 25); |
| elements.scroller.scrollTop = 100; |
| |
| const nonStickyTopY = elements.container.offsetTop + |
| elements.filler.clientHeight; |
| const nonStickyBottomY = nonStickyTopY + elements.sticky.clientHeight; |
| const targetBottomY = elements.scroller.clientHeight + |
| elements.scroller.scrollTop - 25; |
| const stickyOffset = nonStickyBottomY - targetBottomY; |
| |
| assert_equals(elements.sticky.offsetTop, nonStickyTopY - stickyOffset); |
| }, 'after reaching the sticking point the sticky box should be offset'); |
| |
| test(() => { |
| const elements = setupStickyTest('bottom', 25); |
| elements.scroller.scrollTop = 0; |
| assert_equals(elements.sticky.offsetTop, elements.container.offsetTop); |
| }, 'the sticky box should not be pushed outside its containing block'); |
| </script> |
