Source code
Revision control
Copy as Markdown
Other Tools
/**
* Builds a generic structure that looks like:
*
* <div class="scroller"> // 100x200 viewport
* <div class="contents"> // 100x500
* <div class="prepadding"></div> // 100x100
* <div class="container"> // 300x300 containing block
* <div class="filler"></div> // 100x100
* <div class="sticky box"></div> // 100x100
* </div>
* </div>
* </div>
*
* If the sticky direction is 'left' or 'right', the necessary blocks will be
* marked as inline-block and the dimensions above are flipped.
*
* Returns an 'elements' object which has each of the above elements as an
* accessible property.
*/
function setupStickyTest(stickyDirection, stickyOffset) {
const elements = {};
const inline = stickyDirection === 'left' || stickyDirection === 'right';
elements.scroller = document.createElement('div');
elements.scroller.style.position = 'relative';
elements.scroller.style.width = (inline ? '200px' : '100px');
elements.scroller.style.height = (inline ? '100px' : '200px');
// 'hidden' is used here instead of 'scroll' because this prevents
// scrollbars from affecting the size and offset of sticky items.
elements.scroller.style.overflow = 'hidden';
elements.contents = document.createElement('div');
elements.contents.style.height = (inline ? '100%' : '500px');
elements.contents.style.width = (inline ? '500px' : '100%');
elements.prepadding = document.createElement('div');
elements.prepadding.style.height = (inline ? '100%' : '100px');
elements.prepadding.style.width = (inline ? '100px' : '100%');
if (inline)
elements.prepadding.style.display = 'inline-block';
elements.container = document.createElement('div');
elements.container.style.height = (inline ? '100%' : '300px');
elements.container.style.width = (inline ? '300px' : '100%');
if (inline)
elements.container.style.display = 'inline-block';
elements.filler = document.createElement('div');
elements.filler.style.height = (inline ? '100%' : '100px');
elements.filler.style.width = (inline ? '100px' : '100%');
if (inline)
elements.filler.style.display = 'inline-block';
elements.sticky = document.createElement('div');
elements.sticky.style = `${stickyDirection}: ${stickyOffset}px;`;
elements.sticky.style.position = 'sticky';
elements.sticky.style.height = (inline ? '100%' : '100px');
elements.sticky.style.width = (inline ? '100px' : '100%');
elements.sticky.style.backgroundColor = 'green';
if (inline)
elements.sticky.style.display = 'inline-block';
elements.scroller.appendChild(elements.contents);
elements.contents.appendChild(elements.prepadding);
elements.contents.appendChild(elements.container);
elements.container.appendChild(elements.filler);
elements.container.appendChild(elements.sticky);
document.body.appendChild(elements.scroller);
return elements;
}
/**
* Similar to above, but nests a second sticky (named innerSticky) inside the
* sticky element.
*
* In the 'bottom' and 'right' cases, we also inject some padding before the
* innerSticky element, to give it something to push into. This inner padding is
* not exposed.
*/
function setupNestedStickyTest(stickyDirection, outerStickyOffset,
innerStickyOffset) {
const elements = setupStickyTest(stickyDirection, outerStickyOffset);
const inline = stickyDirection === 'left' || stickyDirection === 'right';
if (stickyDirection === 'bottom' || stickyDirection === 'right') {
const innerPadding = document.createElement('div');
innerPadding.style.height = (inline ? '100%' : '50px');
innerPadding.style.width = (inline ? '50px' : '100%');
if (inline)
innerPadding.style.display = 'inline-block';
elements.sticky.appendChild(innerPadding);
}
elements.innerSticky = document.createElement('div');
elements.innerSticky.style = `${stickyDirection}: ${innerStickyOffset}px;`;
elements.innerSticky.style.position = 'sticky';
elements.innerSticky.style.height = (inline ? '100%' : '50px');
elements.innerSticky.style.width = (inline ? '50px' : '100%');
elements.innerSticky.style.backgroundColor = 'blue';
if (inline)
elements.innerSticky.style.display = 'inline-block';
elements.sticky.appendChild(elements.innerSticky);
return elements;
}