/*! instant.page v1.2.2 - (C) 2019 Alexandre Dieulot - https://instant.page/license */ let urlToPreload; let mouseoverTimer; let lastTouchTimestamp; const prefetcher = document.createElement('link'); const isSupported = prefetcher.relList && prefetcher.relList.supports && prefetcher.relList.supports('prefetch'); const isDataSaverEnabled = navigator.connection && navigator.connection.saveData; const allowQueryString = 'instantAllowQueryString' in document.body.dataset; const allowExternalLinks = 'instantAllowExternalLinks' in document.body.dataset; if (isSupported && !isDataSaverEnabled) { prefetcher.rel = 'prefetch'; document.head.appendChild(prefetcher); const eventListenersOptions = { capture: true, passive: true, }; document.addEventListener('touchstart', touchstartListener, eventListenersOptions); document.addEventListener('mouseover', mouseoverListener, eventListenersOptions) } function touchstartListener(event) { /* Chrome on Android calls mouseover before touchcancel so `lastTouchTimestamp` * must be assigned on touchstart to be measured on mouseover. */ lastTouchTimestamp = performance.now(); const linkElement = event.target.closest('a'); if (!isPreloadable(linkElement)) { return } linkElement.addEventListener('touchcancel', touchendAndTouchcancelListener, {passive: true}); linkElement.addEventListener('touchend', touchendAndTouchcancelListener, {passive: true}); urlToPreload = linkElement.href; preload(linkElement.href) } function touchendAndTouchcancelListener() { urlToPreload = undefined; stopPreloading() } function mouseoverListener(event) { if (performance.now() - lastTouchTimestamp < 1100) { return } const linkElement = event.target.closest('a'); if (!isPreloadable(linkElement)) { return } linkElement.addEventListener('mouseout', mouseoutListener, {passive: true}); urlToPreload = linkElement.href; mouseoverTimer = setTimeout(() => { preload(linkElement.href); mouseoverTimer = undefined }, 65) } function mouseoutListener(event) { if (event.relatedTarget && event.target.closest('a') === event.relatedTarget.closest('a')) { return } if (mouseoverTimer) { clearTimeout(mouseoverTimer); mouseoverTimer = undefined } else { urlToPreload = undefined; stopPreloading() } } function isPreloadable(linkElement) { if (!linkElement || !linkElement.href) { return } if (urlToPreload === linkElement.href) { return } const preloadLocation = new URL(linkElement.href); if (!allowExternalLinks && preloadLocation.origin !== location.origin && !('instant' in linkElement.dataset)) { return } if (!['http:', 'https:'].includes(preloadLocation.protocol)) { return } if (preloadLocation.protocol === 'http:' && location.protocol === 'https:') { return } if (!allowQueryString && preloadLocation.search && !('instant' in linkElement.dataset)) { return } if (preloadLocation.hash && preloadLocation.pathname + preloadLocation.search === location.pathname + location.search) { return } if ('noInstant' in linkElement.dataset) { return } return true } function preload(url) { prefetcher.href = url } function stopPreloading() { prefetcher.removeAttribute('href') }