70 lines
2.0 KiB
JavaScript
70 lines
2.0 KiB
JavaScript
// Source from https://github.com/alitaheri/normalize-scroll-left
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let cachedType;
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/**
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* Based on the jquery plugin https://github.com/othree/jquery.rtl-scroll-type
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*
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* Types of scrollLeft, assuming scrollWidth=100 and direction is rtl.
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*
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* Type | <- Most Left | Most Right -> | Initial
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* ---------------- | ------------ | ------------- | -------
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* default | 0 | 100 | 100
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* negative (spec*) | -100 | 0 | 0
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* reverse | 100 | 0 | 0
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*
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* Edge 85: default
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* Safari 14: negative
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* Chrome 85: negative
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* Firefox 81: negative
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* IE11: reverse
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*
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* spec* https://drafts.csswg.org/cssom-view/#dom-window-scroll
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*/
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export function detectScrollType() {
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if (cachedType) {
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return cachedType;
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}
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const dummy = document.createElement('div');
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const container = document.createElement('div');
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container.style.width = '10px';
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container.style.height = '1px';
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dummy.appendChild(container);
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dummy.dir = 'rtl';
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dummy.style.fontSize = '14px';
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dummy.style.width = '4px';
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dummy.style.height = '1px';
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dummy.style.position = 'absolute';
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dummy.style.top = '-1000px';
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dummy.style.overflow = 'scroll';
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document.body.appendChild(dummy);
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cachedType = 'reverse';
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if (dummy.scrollLeft > 0) {
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cachedType = 'default';
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} else {
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dummy.scrollLeft = 1;
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if (dummy.scrollLeft === 0) {
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cachedType = 'negative';
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}
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}
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document.body.removeChild(dummy);
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return cachedType;
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}
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// Based on https://stackoverflow.com/a/24394376
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export function getNormalizedScrollLeft(element, direction) {
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const scrollLeft = element.scrollLeft;
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// Perform the calculations only when direction is rtl to avoid messing up the ltr behavior
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if (direction !== 'rtl') {
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return scrollLeft;
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}
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const type = detectScrollType();
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switch (type) {
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case 'negative':
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return element.scrollWidth - element.clientWidth + scrollLeft;
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case 'reverse':
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return element.scrollWidth - element.clientWidth - scrollLeft;
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default:
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return scrollLeft;
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}
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} |