727 lines
22 KiB
JavaScript
727 lines
22 KiB
JavaScript
/**
|
|
* Copyright 2016 Google Inc. All Rights Reserved.
|
|
*
|
|
* Licensed under the W3C SOFTWARE AND DOCUMENT NOTICE AND LICENSE.
|
|
*
|
|
* https://www.w3.org/Consortium/Legal/2015/copyright-software-and-document
|
|
*
|
|
*/
|
|
|
|
(function(window, document) {
|
|
'use strict';
|
|
|
|
|
|
// Exits early if all IntersectionObserver and IntersectionObserverEntry
|
|
// features are natively supported.
|
|
if ('IntersectionObserver' in window &&
|
|
'IntersectionObserverEntry' in window &&
|
|
'intersectionRatio' in window.IntersectionObserverEntry.prototype) {
|
|
|
|
// Minimal polyfill for Edge 15's lack of `isIntersecting`
|
|
// See: https://github.com/w3c/IntersectionObserver/issues/211
|
|
if (!('isIntersecting' in window.IntersectionObserverEntry.prototype)) {
|
|
Object.defineProperty(window.IntersectionObserverEntry.prototype,
|
|
'isIntersecting', {
|
|
get: function () {
|
|
return this.intersectionRatio > 0;
|
|
}
|
|
});
|
|
}
|
|
return;
|
|
}
|
|
|
|
|
|
/**
|
|
* An IntersectionObserver registry. This registry exists to hold a strong
|
|
* reference to IntersectionObserver instances currently observing a target
|
|
* element. Without this registry, instances without another reference may be
|
|
* garbage collected.
|
|
*/
|
|
var registry = [];
|
|
|
|
|
|
/**
|
|
* Creates the global IntersectionObserverEntry constructor.
|
|
* https://w3c.github.io/IntersectionObserver/#intersection-observer-entry
|
|
* @param {Object} entry A dictionary of instance properties.
|
|
* @constructor
|
|
*/
|
|
function IntersectionObserverEntry(entry) {
|
|
this.time = entry.time;
|
|
this.target = entry.target;
|
|
this.rootBounds = entry.rootBounds;
|
|
this.boundingClientRect = entry.boundingClientRect;
|
|
this.intersectionRect = entry.intersectionRect || getEmptyRect();
|
|
this.isIntersecting = !!entry.intersectionRect;
|
|
|
|
// Calculates the intersection ratio.
|
|
var targetRect = this.boundingClientRect;
|
|
var targetArea = targetRect.width * targetRect.height;
|
|
var intersectionRect = this.intersectionRect;
|
|
var intersectionArea = intersectionRect.width * intersectionRect.height;
|
|
|
|
// Sets intersection ratio.
|
|
if (targetArea) {
|
|
// Round the intersection ratio to avoid floating point math issues:
|
|
// https://github.com/w3c/IntersectionObserver/issues/324
|
|
this.intersectionRatio = Number((intersectionArea / targetArea).toFixed(4));
|
|
} else {
|
|
// If area is zero and is intersecting, sets to 1, otherwise to 0
|
|
this.intersectionRatio = this.isIntersecting ? 1 : 0;
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Creates the global IntersectionObserver constructor.
|
|
* https://w3c.github.io/IntersectionObserver/#intersection-observer-interface
|
|
* @param {Function} callback The function to be invoked after intersection
|
|
* changes have queued. The function is not invoked if the queue has
|
|
* been emptied by calling the `takeRecords` method.
|
|
* @param {Object=} opt_options Optional configuration options.
|
|
* @constructor
|
|
*/
|
|
function IntersectionObserver(callback, opt_options) {
|
|
|
|
var options = opt_options || {};
|
|
|
|
if (typeof callback != 'function') {
|
|
throw new Error('callback must be a function');
|
|
}
|
|
|
|
if (options.root && options.root.nodeType != 1) {
|
|
throw new Error('root must be an Element');
|
|
}
|
|
|
|
// Binds and throttles `this._checkForIntersections`.
|
|
this._checkForIntersections = throttle(
|
|
this._checkForIntersections.bind(this), this.THROTTLE_TIMEOUT);
|
|
|
|
// Private properties.
|
|
this._callback = callback;
|
|
this._observationTargets = [];
|
|
this._queuedEntries = [];
|
|
this._rootMarginValues = this._parseRootMargin(options.rootMargin);
|
|
|
|
// Public properties.
|
|
this.thresholds = this._initThresholds(options.threshold);
|
|
this.root = options.root || null;
|
|
this.rootMargin = this._rootMarginValues.map(function(margin) {
|
|
return margin.value + margin.unit;
|
|
}).join(' ');
|
|
}
|
|
|
|
|
|
/**
|
|
* The minimum interval within which the document will be checked for
|
|
* intersection changes.
|
|
*/
|
|
IntersectionObserver.prototype.THROTTLE_TIMEOUT = 100;
|
|
|
|
|
|
/**
|
|
* The frequency in which the polyfill polls for intersection changes.
|
|
* this can be updated on a per instance basis and must be set prior to
|
|
* calling `observe` on the first target.
|
|
*/
|
|
IntersectionObserver.prototype.POLL_INTERVAL = null;
|
|
|
|
/**
|
|
* Use a mutation observer on the root element
|
|
* to detect intersection changes.
|
|
*/
|
|
IntersectionObserver.prototype.USE_MUTATION_OBSERVER = true;
|
|
|
|
|
|
/**
|
|
* Starts observing a target element for intersection changes based on
|
|
* the thresholds values.
|
|
* @param {Element} target The DOM element to observe.
|
|
*/
|
|
IntersectionObserver.prototype.observe = function(target) {
|
|
var isTargetAlreadyObserved = this._observationTargets.some(function(item) {
|
|
return item.element == target;
|
|
});
|
|
|
|
if (isTargetAlreadyObserved) {
|
|
return;
|
|
}
|
|
|
|
if (!(target && target.nodeType == 1)) {
|
|
throw new Error('target must be an Element');
|
|
}
|
|
|
|
this._registerInstance();
|
|
this._observationTargets.push({element: target, entry: null});
|
|
this._monitorIntersections();
|
|
this._checkForIntersections();
|
|
};
|
|
|
|
|
|
/**
|
|
* Stops observing a target element for intersection changes.
|
|
* @param {Element} target The DOM element to observe.
|
|
*/
|
|
IntersectionObserver.prototype.unobserve = function(target) {
|
|
this._observationTargets =
|
|
this._observationTargets.filter(function(item) {
|
|
|
|
return item.element != target;
|
|
});
|
|
if (!this._observationTargets.length) {
|
|
this._unmonitorIntersections();
|
|
this._unregisterInstance();
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Stops observing all target elements for intersection changes.
|
|
*/
|
|
IntersectionObserver.prototype.disconnect = function() {
|
|
this._observationTargets = [];
|
|
this._unmonitorIntersections();
|
|
this._unregisterInstance();
|
|
};
|
|
|
|
|
|
/**
|
|
* Returns any queue entries that have not yet been reported to the
|
|
* callback and clears the queue. This can be used in conjunction with the
|
|
* callback to obtain the absolute most up-to-date intersection information.
|
|
* @return {Array} The currently queued entries.
|
|
*/
|
|
IntersectionObserver.prototype.takeRecords = function() {
|
|
var records = this._queuedEntries.slice();
|
|
this._queuedEntries = [];
|
|
return records;
|
|
};
|
|
|
|
|
|
/**
|
|
* Accepts the threshold value from the user configuration object and
|
|
* returns a sorted array of unique threshold values. If a value is not
|
|
* between 0 and 1 and error is thrown.
|
|
* @private
|
|
* @param {Array|number=} opt_threshold An optional threshold value or
|
|
* a list of threshold values, defaulting to [0].
|
|
* @return {Array} A sorted list of unique and valid threshold values.
|
|
*/
|
|
IntersectionObserver.prototype._initThresholds = function(opt_threshold) {
|
|
var threshold = opt_threshold || [0];
|
|
if (!Array.isArray(threshold)) threshold = [threshold];
|
|
|
|
return threshold.sort().filter(function(t, i, a) {
|
|
if (typeof t != 'number' || isNaN(t) || t < 0 || t > 1) {
|
|
throw new Error('threshold must be a number between 0 and 1 inclusively');
|
|
}
|
|
return t !== a[i - 1];
|
|
});
|
|
};
|
|
|
|
|
|
/**
|
|
* Accepts the rootMargin value from the user configuration object
|
|
* and returns an array of the four margin values as an object containing
|
|
* the value and unit properties. If any of the values are not properly
|
|
* formatted or use a unit other than px or %, and error is thrown.
|
|
* @private
|
|
* @param {string=} opt_rootMargin An optional rootMargin value,
|
|
* defaulting to '0px'.
|
|
* @return {Array<Object>} An array of margin objects with the keys
|
|
* value and unit.
|
|
*/
|
|
IntersectionObserver.prototype._parseRootMargin = function(opt_rootMargin) {
|
|
var marginString = opt_rootMargin || '0px';
|
|
var margins = marginString.split(/\s+/).map(function(margin) {
|
|
var parts = /^(-?\d*\.?\d+)(px|%)$/.exec(margin);
|
|
if (!parts) {
|
|
throw new Error('rootMargin must be specified in pixels or percent');
|
|
}
|
|
return {value: parseFloat(parts[1]), unit: parts[2]};
|
|
});
|
|
|
|
// Handles shorthand.
|
|
margins[1] = margins[1] || margins[0];
|
|
margins[2] = margins[2] || margins[0];
|
|
margins[3] = margins[3] || margins[1];
|
|
|
|
return margins;
|
|
};
|
|
|
|
|
|
/**
|
|
* Starts polling for intersection changes if the polling is not already
|
|
* happening, and if the page's visibility state is visible.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._monitorIntersections = function() {
|
|
if (!this._monitoringIntersections) {
|
|
this._monitoringIntersections = true;
|
|
|
|
// If a poll interval is set, use polling instead of listening to
|
|
// resize and scroll events or DOM mutations.
|
|
if (this.POLL_INTERVAL) {
|
|
this._monitoringInterval = setInterval(
|
|
this._checkForIntersections, this.POLL_INTERVAL);
|
|
}
|
|
else {
|
|
addEvent(window, 'resize', this._checkForIntersections, true);
|
|
addEvent(document, 'scroll', this._checkForIntersections, true);
|
|
|
|
if (this.USE_MUTATION_OBSERVER && 'MutationObserver' in window) {
|
|
this._domObserver = new MutationObserver(this._checkForIntersections);
|
|
this._domObserver.observe(document, {
|
|
attributes: true,
|
|
childList: true,
|
|
characterData: true,
|
|
subtree: true
|
|
});
|
|
}
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Stops polling for intersection changes.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._unmonitorIntersections = function() {
|
|
if (this._monitoringIntersections) {
|
|
this._monitoringIntersections = false;
|
|
|
|
clearInterval(this._monitoringInterval);
|
|
this._monitoringInterval = null;
|
|
|
|
removeEvent(window, 'resize', this._checkForIntersections, true);
|
|
removeEvent(document, 'scroll', this._checkForIntersections, true);
|
|
|
|
if (this._domObserver) {
|
|
this._domObserver.disconnect();
|
|
this._domObserver = null;
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Scans each observation target for intersection changes and adds them
|
|
* to the internal entries queue. If new entries are found, it
|
|
* schedules the callback to be invoked.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._checkForIntersections = function() {
|
|
var rootIsInDom = this._rootIsInDom();
|
|
var rootRect = rootIsInDom ? this._getRootRect() : getEmptyRect();
|
|
|
|
this._observationTargets.forEach(function(item) {
|
|
var target = item.element;
|
|
var targetRect = getBoundingClientRect(target);
|
|
var rootContainsTarget = this._rootContainsTarget(target);
|
|
var oldEntry = item.entry;
|
|
var intersectionRect = rootIsInDom && rootContainsTarget &&
|
|
this._computeTargetAndRootIntersection(target, rootRect);
|
|
|
|
var newEntry = item.entry = new IntersectionObserverEntry({
|
|
time: now(),
|
|
target: target,
|
|
boundingClientRect: targetRect,
|
|
rootBounds: rootRect,
|
|
intersectionRect: intersectionRect
|
|
});
|
|
|
|
if (!oldEntry) {
|
|
this._queuedEntries.push(newEntry);
|
|
} else if (rootIsInDom && rootContainsTarget) {
|
|
// If the new entry intersection ratio has crossed any of the
|
|
// thresholds, add a new entry.
|
|
if (this._hasCrossedThreshold(oldEntry, newEntry)) {
|
|
this._queuedEntries.push(newEntry);
|
|
}
|
|
} else {
|
|
// If the root is not in the DOM or target is not contained within
|
|
// root but the previous entry for this target had an intersection,
|
|
// add a new record indicating removal.
|
|
if (oldEntry && oldEntry.isIntersecting) {
|
|
this._queuedEntries.push(newEntry);
|
|
}
|
|
}
|
|
}, this);
|
|
|
|
if (this._queuedEntries.length) {
|
|
this._callback(this.takeRecords(), this);
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Accepts a target and root rect computes the intersection between then
|
|
* following the algorithm in the spec.
|
|
* TODO(philipwalton): at this time clip-path is not considered.
|
|
* https://w3c.github.io/IntersectionObserver/#calculate-intersection-rect-algo
|
|
* @param {Element} target The target DOM element
|
|
* @param {Object} rootRect The bounding rect of the root after being
|
|
* expanded by the rootMargin value.
|
|
* @return {?Object} The final intersection rect object or undefined if no
|
|
* intersection is found.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._computeTargetAndRootIntersection =
|
|
function(target, rootRect) {
|
|
|
|
// If the element isn't displayed, an intersection can't happen.
|
|
if (window.getComputedStyle(target).display == 'none') return;
|
|
|
|
var targetRect = getBoundingClientRect(target);
|
|
var intersectionRect = targetRect;
|
|
var parent = getParentNode(target);
|
|
var atRoot = false;
|
|
|
|
while (!atRoot) {
|
|
var parentRect = null;
|
|
var parentComputedStyle = parent.nodeType == 1 ?
|
|
window.getComputedStyle(parent) : {};
|
|
|
|
// If the parent isn't displayed, an intersection can't happen.
|
|
if (parentComputedStyle.display == 'none') return;
|
|
|
|
if (parent == this.root || parent == document) {
|
|
atRoot = true;
|
|
parentRect = rootRect;
|
|
} else {
|
|
// If the element has a non-visible overflow, and it's not the <body>
|
|
// or <html> element, update the intersection rect.
|
|
// Note: <body> and <html> cannot be clipped to a rect that's not also
|
|
// the document rect, so no need to compute a new intersection.
|
|
if (parent != document.body &&
|
|
parent != document.documentElement &&
|
|
parentComputedStyle.overflow != 'visible') {
|
|
parentRect = getBoundingClientRect(parent);
|
|
}
|
|
}
|
|
|
|
// If either of the above conditionals set a new parentRect,
|
|
// calculate new intersection data.
|
|
if (parentRect) {
|
|
intersectionRect = computeRectIntersection(parentRect, intersectionRect);
|
|
|
|
if (!intersectionRect) break;
|
|
}
|
|
parent = getParentNode(parent);
|
|
}
|
|
return intersectionRect;
|
|
};
|
|
|
|
|
|
/**
|
|
* Returns the root rect after being expanded by the rootMargin value.
|
|
* @return {Object} The expanded root rect.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._getRootRect = function() {
|
|
var rootRect;
|
|
if (this.root) {
|
|
rootRect = getBoundingClientRect(this.root);
|
|
} else {
|
|
// Use <html>/<body> instead of window since scroll bars affect size.
|
|
var html = document.documentElement;
|
|
var body = document.body;
|
|
rootRect = {
|
|
top: 0,
|
|
left: 0,
|
|
right: html.clientWidth || body.clientWidth,
|
|
width: html.clientWidth || body.clientWidth,
|
|
bottom: html.clientHeight || body.clientHeight,
|
|
height: html.clientHeight || body.clientHeight
|
|
};
|
|
}
|
|
return this._expandRectByRootMargin(rootRect);
|
|
};
|
|
|
|
|
|
/**
|
|
* Accepts a rect and expands it by the rootMargin value.
|
|
* @param {Object} rect The rect object to expand.
|
|
* @return {Object} The expanded rect.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._expandRectByRootMargin = function(rect) {
|
|
var margins = this._rootMarginValues.map(function(margin, i) {
|
|
return margin.unit == 'px' ? margin.value :
|
|
margin.value * (i % 2 ? rect.width : rect.height) / 100;
|
|
});
|
|
var newRect = {
|
|
top: rect.top - margins[0],
|
|
right: rect.right + margins[1],
|
|
bottom: rect.bottom + margins[2],
|
|
left: rect.left - margins[3]
|
|
};
|
|
newRect.width = newRect.right - newRect.left;
|
|
newRect.height = newRect.bottom - newRect.top;
|
|
|
|
return newRect;
|
|
};
|
|
|
|
|
|
/**
|
|
* Accepts an old and new entry and returns true if at least one of the
|
|
* threshold values has been crossed.
|
|
* @param {?IntersectionObserverEntry} oldEntry The previous entry for a
|
|
* particular target element or null if no previous entry exists.
|
|
* @param {IntersectionObserverEntry} newEntry The current entry for a
|
|
* particular target element.
|
|
* @return {boolean} Returns true if a any threshold has been crossed.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._hasCrossedThreshold =
|
|
function(oldEntry, newEntry) {
|
|
|
|
// To make comparing easier, an entry that has a ratio of 0
|
|
// but does not actually intersect is given a value of -1
|
|
var oldRatio = oldEntry && oldEntry.isIntersecting ?
|
|
oldEntry.intersectionRatio || 0 : -1;
|
|
var newRatio = newEntry.isIntersecting ?
|
|
newEntry.intersectionRatio || 0 : -1;
|
|
|
|
// Ignore unchanged ratios
|
|
if (oldRatio === newRatio) return;
|
|
|
|
for (var i = 0; i < this.thresholds.length; i++) {
|
|
var threshold = this.thresholds[i];
|
|
|
|
// Return true if an entry matches a threshold or if the new ratio
|
|
// and the old ratio are on the opposite sides of a threshold.
|
|
if (threshold == oldRatio || threshold == newRatio ||
|
|
threshold < oldRatio !== threshold < newRatio) {
|
|
return true;
|
|
}
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Returns whether or not the root element is an element and is in the DOM.
|
|
* @return {boolean} True if the root element is an element and is in the DOM.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._rootIsInDom = function() {
|
|
return !this.root || containsDeep(document, this.root);
|
|
};
|
|
|
|
|
|
/**
|
|
* Returns whether or not the target element is a child of root.
|
|
* @param {Element} target The target element to check.
|
|
* @return {boolean} True if the target element is a child of root.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._rootContainsTarget = function(target) {
|
|
return containsDeep(this.root || document, target);
|
|
};
|
|
|
|
|
|
/**
|
|
* Adds the instance to the global IntersectionObserver registry if it isn't
|
|
* already present.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._registerInstance = function() {
|
|
if (registry.indexOf(this) < 0) {
|
|
registry.push(this);
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Removes the instance from the global IntersectionObserver registry.
|
|
* @private
|
|
*/
|
|
IntersectionObserver.prototype._unregisterInstance = function() {
|
|
var index = registry.indexOf(this);
|
|
if (index != -1) registry.splice(index, 1);
|
|
};
|
|
|
|
|
|
/**
|
|
* Returns the result of the performance.now() method or null in browsers
|
|
* that don't support the API.
|
|
* @return {number} The elapsed time since the page was requested.
|
|
*/
|
|
function now() {
|
|
return window.performance && performance.now && performance.now();
|
|
}
|
|
|
|
|
|
/**
|
|
* Throttles a function and delays its execution, so it's only called at most
|
|
* once within a given time period.
|
|
* @param {Function} fn The function to throttle.
|
|
* @param {number} timeout The amount of time that must pass before the
|
|
* function can be called again.
|
|
* @return {Function} The throttled function.
|
|
*/
|
|
function throttle(fn, timeout) {
|
|
var timer = null;
|
|
return function () {
|
|
if (!timer) {
|
|
timer = setTimeout(function() {
|
|
fn();
|
|
timer = null;
|
|
}, timeout);
|
|
}
|
|
};
|
|
}
|
|
|
|
|
|
/**
|
|
* Adds an event handler to a DOM node ensuring cross-browser compatibility.
|
|
* @param {Node} node The DOM node to add the event handler to.
|
|
* @param {string} event The event name.
|
|
* @param {Function} fn The event handler to add.
|
|
* @param {boolean} opt_useCapture Optionally adds the even to the capture
|
|
* phase. Note: this only works in modern browsers.
|
|
*/
|
|
function addEvent(node, event, fn, opt_useCapture) {
|
|
if (typeof node.addEventListener == 'function') {
|
|
node.addEventListener(event, fn, opt_useCapture || false);
|
|
}
|
|
else if (typeof node.attachEvent == 'function') {
|
|
node.attachEvent('on' + event, fn);
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Removes a previously added event handler from a DOM node.
|
|
* @param {Node} node The DOM node to remove the event handler from.
|
|
* @param {string} event The event name.
|
|
* @param {Function} fn The event handler to remove.
|
|
* @param {boolean} opt_useCapture If the event handler was added with this
|
|
* flag set to true, it should be set to true here in order to remove it.
|
|
*/
|
|
function removeEvent(node, event, fn, opt_useCapture) {
|
|
if (typeof node.removeEventListener == 'function') {
|
|
node.removeEventListener(event, fn, opt_useCapture || false);
|
|
}
|
|
else if (typeof node.detatchEvent == 'function') {
|
|
node.detatchEvent('on' + event, fn);
|
|
}
|
|
}
|
|
|
|
|
|
/**
|
|
* Returns the intersection between two rect objects.
|
|
* @param {Object} rect1 The first rect.
|
|
* @param {Object} rect2 The second rect.
|
|
* @return {?Object} The intersection rect or undefined if no intersection
|
|
* is found.
|
|
*/
|
|
function computeRectIntersection(rect1, rect2) {
|
|
var top = Math.max(rect1.top, rect2.top);
|
|
var bottom = Math.min(rect1.bottom, rect2.bottom);
|
|
var left = Math.max(rect1.left, rect2.left);
|
|
var right = Math.min(rect1.right, rect2.right);
|
|
var width = right - left;
|
|
var height = bottom - top;
|
|
|
|
return (width >= 0 && height >= 0) && {
|
|
top: top,
|
|
bottom: bottom,
|
|
left: left,
|
|
right: right,
|
|
width: width,
|
|
height: height
|
|
};
|
|
}
|
|
|
|
|
|
/**
|
|
* Shims the native getBoundingClientRect for compatibility with older IE.
|
|
* @param {Element} el The element whose bounding rect to get.
|
|
* @return {Object} The (possibly shimmed) rect of the element.
|
|
*/
|
|
function getBoundingClientRect(el) {
|
|
var rect;
|
|
|
|
try {
|
|
rect = el.getBoundingClientRect();
|
|
} catch (err) {
|
|
// Ignore Windows 7 IE11 "Unspecified error"
|
|
// https://github.com/w3c/IntersectionObserver/pull/205
|
|
}
|
|
|
|
if (!rect) return getEmptyRect();
|
|
|
|
// Older IE
|
|
if (!(rect.width && rect.height)) {
|
|
rect = {
|
|
top: rect.top,
|
|
right: rect.right,
|
|
bottom: rect.bottom,
|
|
left: rect.left,
|
|
width: rect.right - rect.left,
|
|
height: rect.bottom - rect.top
|
|
};
|
|
}
|
|
return rect;
|
|
}
|
|
|
|
|
|
/**
|
|
* Returns an empty rect object. An empty rect is returned when an element
|
|
* is not in the DOM.
|
|
* @return {Object} The empty rect.
|
|
*/
|
|
function getEmptyRect() {
|
|
return {
|
|
top: 0,
|
|
bottom: 0,
|
|
left: 0,
|
|
right: 0,
|
|
width: 0,
|
|
height: 0
|
|
};
|
|
}
|
|
|
|
/**
|
|
* Checks to see if a parent element contains a child element (including inside
|
|
* shadow DOM).
|
|
* @param {Node} parent The parent element.
|
|
* @param {Node} child The child element.
|
|
* @return {boolean} True if the parent node contains the child node.
|
|
*/
|
|
function containsDeep(parent, child) {
|
|
var node = child;
|
|
while (node) {
|
|
if (node == parent) return true;
|
|
|
|
node = getParentNode(node);
|
|
}
|
|
return false;
|
|
}
|
|
|
|
|
|
/**
|
|
* Gets the parent node of an element or its host element if the parent node
|
|
* is a shadow root.
|
|
* @param {Node} node The node whose parent to get.
|
|
* @return {Node|null} The parent node or null if no parent exists.
|
|
*/
|
|
function getParentNode(node) {
|
|
var parent = node.parentNode;
|
|
|
|
if (parent && parent.nodeType == 11 && parent.host) {
|
|
// If the parent is a shadow root, return the host element.
|
|
return parent.host;
|
|
}
|
|
return parent;
|
|
}
|
|
|
|
|
|
// Exposes the constructors globally.
|
|
window.IntersectionObserver = IntersectionObserver;
|
|
window.IntersectionObserverEntry = IntersectionObserverEntry;
|
|
|
|
}(window, document));
|