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var spy = function () {
var elems = $(":header");
if (elems.length == 0) {
return;
}
var currentTop = $(window).scrollTop();
var currentBottom = $(window).scrollTop() + $(window).height();
var pageBottom = $('#EOF').offset().top;
var meetUnread = false
var currentIndex = -1
elems.each(function (idx) {
var elemTop = $(this).offset().top;
var id = $(this).attr('id');
var navElem = $('#' + id + '-nav');
if (currentTop + $(this).height() >= elemTop || currentBottom >= pageBottom) {
navElem.addClass('toc-active');
} else {
if (meetUnread == false) {
meetUnread = true
currentIndex = idx - 1
}
navElem.removeClass('toc-active');
}
})
if (currentIndex == -1) {
currentIndex = elems.length - 1;
}
//console.log(elems[currentIndex].id);
//Collapse them
collapseOthers("#" + elems[currentIndex].id + "-nav");
}
var collapseOthers = function (currentId) {
//console.log(currentId);
$(currentId).parents(".collapse").each(function (idx) {
$(this).collapse("show");
});
$(currentId).parent().next().filter(".collapse").collapse("show");
$(".collapse").not($(currentId).parents()).not($(currentId).parent().next()).each(function (idx) {
$(this).collapse("hide");
});
}
$().ready(function () {
spy();
$(window).bind('scroll', debounce(spy, 250, { 'maxWait': 1000 }));
});
//From https://github.com/lodash/lodash/blob/master/debounce.js
// and https://github.com/lodash/lodash/blob/master/isObject.js
function debounce(func, wait, options) {
let lastArgs,
lastThis,
maxWait,
result,
timerId,
lastCallTime
let lastInvokeTime = 0
let leading = false
let maxing = false
let trailing = true
// Bypass `requestAnimationFrame` by explicitly setting `wait=0`.
const useRAF = (!wait && wait !== 0 && typeof root.requestAnimationFrame === 'function')
if (typeof func !== 'function') {
throw new TypeError('Expected a function')
}
function isObject(value) {
const type = typeof value
return value != null && (type === 'object' || type === 'function')
}
wait = +wait || 0
if (isObject(options)) {
leading = !!options.leading
maxing = 'maxWait' in options
maxWait = maxing ? Math.max(+options.maxWait || 0, wait) : maxWait
trailing = 'trailing' in options ? !!options.trailing : trailing
}
function invokeFunc(time) {
const args = lastArgs
const thisArg = lastThis
lastArgs = lastThis = undefined
lastInvokeTime = time
result = func.apply(thisArg, args)
return result
}
function startTimer(pendingFunc, wait) {
if (useRAF) {
root.cancelAnimationFrame(timerId)
return root.requestAnimationFrame(pendingFunc)
}
return setTimeout(pendingFunc, wait)
}
function cancelTimer(id) {
if (useRAF) {
return root.cancelAnimationFrame(id)
}
clearTimeout(id)
}
function leadingEdge(time) {
// Reset any `maxWait` timer.
lastInvokeTime = time
// Start the timer for the trailing edge.
timerId = startTimer(timerExpired, wait)
// Invoke the leading edge.
return leading ? invokeFunc(time) : result
}
function remainingWait(time) {
const timeSinceLastCall = time - lastCallTime
const timeSinceLastInvoke = time - lastInvokeTime
const timeWaiting = wait - timeSinceLastCall
return maxing
? Math.min(timeWaiting, maxWait - timeSinceLastInvoke)
: timeWaiting
}
function shouldInvoke(time) {
const timeSinceLastCall = time - lastCallTime
const timeSinceLastInvoke = time - lastInvokeTime
// Either this is the first call, activity has stopped and we're at the
// trailing edge, the system time has gone backwards and we're treating
// it as the trailing edge, or we've hit the `maxWait` limit.
return (lastCallTime === undefined || (timeSinceLastCall >= wait) ||
(timeSinceLastCall < 0) || (maxing && timeSinceLastInvoke >= maxWait))
}
function timerExpired() {
const time = Date.now()
if (shouldInvoke(time)) {
return trailingEdge(time)
}
// Restart the timer.
timerId = startTimer(timerExpired, remainingWait(time))
}
function trailingEdge(time) {
timerId = undefined
// Only invoke if we have `lastArgs` which means `func` has been
// debounced at least once.
if (trailing && lastArgs) {
return invokeFunc(time)
}
lastArgs = lastThis = undefined
return result
}
function cancel() {
if (timerId !== undefined) {
cancelTimer(timerId)
}
lastInvokeTime = 0
lastArgs = lastCallTime = lastThis = timerId = undefined
}
function flush() {
return timerId === undefined ? result : trailingEdge(Date.now())
}
function pending() {
return timerId !== undefined
}
function debounced(...args) {
const time = Date.now()
const isInvoking = shouldInvoke(time)
lastArgs = args
lastThis = this
lastCallTime = time
if (isInvoking) {
if (timerId === undefined) {
return leadingEdge(lastCallTime)
}
if (maxing) {
// Handle invocations in a tight loop.
timerId = startTimer(timerExpired, wait)
return invokeFunc(lastCallTime)
}
}
if (timerId === undefined) {
timerId = startTimer(timerExpired, wait)
}
return result
}
debounced.cancel = cancel
debounced.flush = flush
debounced.pending = pending
return debounced
}
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