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zenscroll.js
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zenscroll.js
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/**
* Zenscroll 3.1.0
* https://github.com/zengabor/zenscroll/
*
* Copyright 2015–2016 Gabor Lenard
*
* This is free and unencumbered software released into the public domain.
*
* Anyone is free to copy, modify, publish, use, compile, sell, or
* distribute this software, either in source code form or as a compiled
* binary, for any purpose, commercial or non-commercial, and by any
* means.
*
* In jurisdictions that recognize copyright laws, the author or authors
* of this software dedicate any and all copyright interest in the
* software to the public domain. We make this dedication for the benefit
* of the public at large and to the detriment of our heirs and
* successors. We intend this dedication to be an overt act of
* relinquishment in perpetuity of all present and future rights to this
* software under copyright law.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
* IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
* OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
* ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
* OTHER DEALINGS IN THE SOFTWARE.
*
* For more information, please refer to <http://unlicense.org>
*
*/
/*jshint devel:true, asi:true */
/*global define, module */
(function (root, factory) {
if (typeof define === "function" && define.amd) {
define([], factory())
} else if (typeof module === "object" && module.exports) {
module.exports = factory()
} else {
root.zenscroll = factory()
}
}(this, function () {
"use strict"
// Exit if it’s not a browser environment:
if (!window || !document) {
return {}
}
var createScroller = function (scrollContainer, defaultDuration, edgeOffset) {
defaultDuration = defaultDuration || 999 //ms
if (!edgeOffset && edgeOffset !== 0) {
// When scrolling, this amount of distance is kept from the edges of the scrollContainer:
edgeOffset = 9 //px
}
var scrollTimeoutId
var docElem = document.documentElement
// Detect if the browser already supports native smooth scrolling (e.g., Firefox 36+ and Chrome 49+) and it is enabled:
var nativeSmoothScrollEnabled = function () {
return ("getComputedStyle" in window) &&
window.getComputedStyle(scrollContainer ? scrollContainer : document.body)["scroll-behavior"] === "smooth"
}
var getScrollTop = function () {
return scrollContainer ? scrollContainer.scrollTop : (window.scrollY || docElem.scrollTop)
}
var getViewHeight = function () {
return scrollContainer ?
Math.min(scrollContainer.offsetHeight, window.innerHeight) :
window.innerHeight || docElem.clientHeight
}
var getRelativeTopOf = function (elem) {
if (scrollContainer) {
return elem.offsetTop - scrollContainer.offsetTop
} else {
return elem.getBoundingClientRect().top + getScrollTop() - docElem.offsetTop
}
}
/**
* Immediately stops the current smooth scroll operation
*/
var stopScroll = function () {
clearTimeout(scrollTimeoutId)
scrollTimeoutId = 0
}
/**
* Scrolls to a specific vertical position in the document.
*
* @param {endY} The vertical position within the document.
* @param {duration} Optionally the duration of the scroll operation.
* If 0 or not provided it is automatically calculated based on the
* distance and the default duration.
*/
var scrollToY = function (endY, duration, onDone) {
stopScroll()
if (nativeSmoothScrollEnabled()) {
(scrollContainer || window).scrollTo(0, endY)
if (onDone) {
onDone()
}
} else {
var startY = getScrollTop()
var distance = Math.max(endY,0) - startY
duration = duration || Math.min(Math.abs(distance), defaultDuration)
var startTime = new Date().getTime();
(function loopScroll() {
scrollTimeoutId = setTimeout(function () {
var p = Math.min((new Date().getTime() - startTime) / duration, 1) // percentage
var y = Math.max(Math.floor(startY + distance*(p < 0.5 ? 2*p*p : p*(4 - p*2)-1)), 0)
if (scrollContainer) {
scrollContainer.scrollTop = y
} else {
window.scrollTo(0, y)
}
if (p < 1 && (getViewHeight() + y) < (scrollContainer || docElem).scrollHeight) {
loopScroll()
} else {
setTimeout(stopScroll, 99) // with cooldown time
if (onDone) {
onDone()
}
}
}, 9)
})()
}
}
/**
* Scrolls to the top of a specific element.
*
* @param {elem} The element.
* @param {duration} Optionally the duration of the scroll operation.
* A value of 0 is ignored.
*/
var scrollToElem = function (elem, duration, onDone) {
scrollToY(getRelativeTopOf(elem) - edgeOffset, duration, onDone)
}
/**
* Scrolls an element into view if necessary.
*
* @param {elem} The element.
* @param {duration} Optionally the duration of the scroll operation.
* A value of 0 is ignored.
*/
var scrollIntoView = function (elem, duration, onDone) {
var elemScrollHeight = elem.getBoundingClientRect().height + 2*edgeOffset
var vHeight = getViewHeight()
var elemTop = getRelativeTopOf(elem)
var elemBottom = elemTop + elemScrollHeight - edgeOffset
var scrollTop = getScrollTop()
if ((elemTop - scrollTop) < edgeOffset || elemScrollHeight > vHeight) {
// Element is clipped at top or is higher than screen.
scrollToElem(elem, duration, onDone)
} else if ((scrollTop + vHeight - elemBottom) < 0) {
// Element is clipped at the bottom.
scrollToY(elemBottom - vHeight, duration, onDone)
} else if (onDone) {
onDone()
}
}
/**
* Scrolls to the center of an element.
*
* @param {elem} The element.
* @param {duration} Optionally the duration of the scroll operation.
* @param {offset} Optionally the offset of the top of the element from the center of the screen.
* A value of 0 is ignored.
*/
var scrollToCenterOf = function (elem, duration, offset, onDone) {
scrollToY(
Math.max(
getRelativeTopOf(elem) - getViewHeight()/2 + (offset || elem.getBoundingClientRect().height/2),
0
),
duration,
onDone
)
}
/**
* Changes default settings for this scroller.
*
* @param {newDefaultDuration} New value for default duration, used for each scroll method by default.
* Ignored if 0 or falsy.
* @param {newEdgeOffset} New value for the edge offset, used by each scroll method by default.
*/
var setup = function (newDefaultDuration, newEdgeOffset) {
if (newDefaultDuration) {
defaultDuration = newDefaultDuration
}
if (newEdgeOffset === 0 || newEdgeOffset) {
edgeOffset = newEdgeOffset
}
}
return {
setup: setup,
to: scrollToElem,
toY: scrollToY,
intoView: scrollIntoView,
center: scrollToCenterOf,
stop: stopScroll,
moving: function () { return !!scrollTimeoutId }
}
}
// Create a scroller for the browser window, omitting parameters:
var defaultScroller = createScroller()
// Create listeners for the documentElement only & exclude IE8-
if ("addEventListener" in window && document.body.style.scrollBehavior !== "smooth" && !window.noZensmooth) {
var replaceUrl = function (hash) {
try {
history.replaceState({}, "", window.location.href.split("#")[0] + hash)
} catch (e) {
// To avoid the Security exception in Chrome when the page was opened via the file protocol, e.g., file://index.html
}
}
window.addEventListener("click", function (event) {
var anchor = event.target
while (anchor && anchor.tagName !== "A") {
anchor = anchor.parentNode
}
// Only handle links that were clicked with the primary button, without modifier keys:
if (!anchor || event.which !== 1 || event.shiftKey || event.metaKey || event.ctrlKey || event.altKey) {
return
}
var href = anchor.getAttribute("href") || ""
if (href.indexOf("#") === 0) {
if (href === "#") {
event.preventDefault()
defaultScroller.toY(0)
replaceUrl("")
} else {
var targetId = anchor.hash.substring(1)
var targetElem = document.getElementById(targetId)
if (targetElem) {
event.preventDefault()
defaultScroller.to(targetElem)
replaceUrl("#" + targetId)
}
}
}
}, false)
}
return {
// Expose the "constructor" that can create a new scroller:
createScroller: createScroller,
// Surface the methods of the default scroller:
setup: defaultScroller.setup,
to: defaultScroller.to,
toY: defaultScroller.toY,
intoView: defaultScroller.intoView,
center: defaultScroller.center,
stop: defaultScroller.stop,
moving: defaultScroller.moving
}
}));