resources/lib/intersection-observer/intersection-observer.js
/**
* 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() {
'use strict';
// Exit early if we're not running in a browser.
if (typeof window !== 'object') {
return;
}
// Exit 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;
}
/**
* Returns the embedding frame element, if any.
* @param {!Document} doc
* @return {!Element}
*/
function getFrameElement(doc) {
try {
return doc.defaultView && doc.defaultView.frameElement || null;
} catch (e) {
// Ignore the error.
return null;
}
}
/**
* A local reference to the root document.
*/
var document = (function(startDoc) {
var doc = startDoc;
var frame = getFrameElement(doc);
while (frame) {
doc = frame.ownerDocument;
frame = getFrameElement(doc);
}
return doc;
})(window.document);
/**
* 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 = [];
/**
* The signal updater for cross-origin intersection. When not null, it means
* that the polyfill is configured to work in a cross-origin mode.
* @type {function(DOMRect|ClientRect, DOMRect|ClientRect)}
*/
var crossOriginUpdater = null;
/**
* The current cross-origin intersection. Only used in the cross-origin mode.
* @type {DOMRect|ClientRect}
*/
var crossOriginRect = null;
/**
* 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 = ensureDOMRect(entry.rootBounds);
this.boundingClientRect = ensureDOMRect(entry.boundingClientRect);
this.intersectionRect = ensureDOMRect(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 &&
options.root.nodeType != 9
) {
throw new Error('root must be a Document or 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(' ');
/** @private @const {!Array<!Document>} */
this._monitoringDocuments = [];
/** @private @const {!Array<function()>} */
this._monitoringUnsubscribes = [];
}
/**
* 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;
/**
* Sets up the polyfill in the cross-origin mode. The result is the
* updater function that accepts two arguments: `boundingClientRect` and
* `intersectionRect` - just as these fields would be available to the
* parent via `IntersectionObserverEntry`. This function should be called
* each time the iframe receives intersection information from the parent
* window, e.g. via messaging.
* @return {function(DOMRect|ClientRect, DOMRect|ClientRect)}
*/
IntersectionObserver._setupCrossOriginUpdater = function() {
if (!crossOriginUpdater) {
/**
* @param {DOMRect|ClientRect} boundingClientRect
* @param {DOMRect|ClientRect} intersectionRect
*/
crossOriginUpdater = function(boundingClientRect, intersectionRect) {
if (!boundingClientRect || !intersectionRect) {
crossOriginRect = getEmptyRect();
} else {
crossOriginRect = convertFromParentRect(boundingClientRect, intersectionRect);
}
registry.forEach(function(observer) {
observer._checkForIntersections();
});
};
}
return crossOriginUpdater;
};
/**
* Resets the cross-origin mode.
*/
IntersectionObserver._resetCrossOriginUpdater = function() {
crossOriginUpdater = null;
crossOriginRect = null;
};
/**
* 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(target.ownerDocument);
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;
});
this._unmonitorIntersections(target.ownerDocument);
if (this._observationTargets.length == 0) {
this._unregisterInstance();
}
};
/**
* Stops observing all target elements for intersection changes.
*/
IntersectionObserver.prototype.disconnect = function() {
this._observationTargets = [];
this._unmonitorAllIntersections();
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.
* @param {!Document} doc
* @private
*/
IntersectionObserver.prototype._monitorIntersections = function(doc) {
var win = doc.defaultView;
if (!win) {
// Already destroyed.
return;
}
if (this._monitoringDocuments.indexOf(doc) != -1) {
// Already monitoring.
return;
}
// Private state for monitoring.
var callback = this._checkForIntersections;
var monitoringInterval = null;
var domObserver = null;
// If a poll interval is set, use polling instead of listening to
// resize and scroll events or DOM mutations.
if (this.POLL_INTERVAL) {
monitoringInterval = win.setInterval(callback, this.POLL_INTERVAL);
} else {
addEvent(win, 'resize', callback, true);
addEvent(doc, 'scroll', callback, true);
if (this.USE_MUTATION_OBSERVER && 'MutationObserver' in win) {
domObserver = new win.MutationObserver(callback);
domObserver.observe(doc, {
attributes: true,
childList: true,
characterData: true,
subtree: true
});
}
}
this._monitoringDocuments.push(doc);
this._monitoringUnsubscribes.push(function() {
// Get the window object again. When a friendly iframe is destroyed, it
// will be null.
var win = doc.defaultView;
if (win) {
if (monitoringInterval) {
win.clearInterval(monitoringInterval);
}
removeEvent(win, 'resize', callback, true);
}
removeEvent(doc, 'scroll', callback, true);
if (domObserver) {
domObserver.disconnect();
}
});
// Also monitor the parent.
var rootDoc =
(this.root && (this.root.ownerDocument || this.root)) || document;
if (doc != rootDoc) {
var frame = getFrameElement(doc);
if (frame) {
this._monitorIntersections(frame.ownerDocument);
}
}
};
/**
* Stops polling for intersection changes.
* @param {!Document} doc
* @private
*/
IntersectionObserver.prototype._unmonitorIntersections = function(doc) {
var index = this._monitoringDocuments.indexOf(doc);
if (index == -1) {
return;
}
var rootDoc =
(this.root && (this.root.ownerDocument || this.root)) || document;
// Check if any dependent targets are still remaining.
var hasDependentTargets =
this._observationTargets.some(function(item) {
var itemDoc = item.element.ownerDocument;
// Target is in this context.
if (itemDoc == doc) {
return true;
}
// Target is nested in this context.
while (itemDoc && itemDoc != rootDoc) {
var frame = getFrameElement(itemDoc);
itemDoc = frame && frame.ownerDocument;
if (itemDoc == doc) {
return true;
}
}
return false;
});
if (hasDependentTargets) {
return;
}
// Unsubscribe.
var unsubscribe = this._monitoringUnsubscribes[index];
this._monitoringDocuments.splice(index, 1);
this._monitoringUnsubscribes.splice(index, 1);
unsubscribe();
// Also unmonitor the parent.
if (doc != rootDoc) {
var frame = getFrameElement(doc);
if (frame) {
this._unmonitorIntersections(frame.ownerDocument);
}
}
};
/**
* Stops polling for intersection changes.
* @param {!Document} doc
* @private
*/
IntersectionObserver.prototype._unmonitorAllIntersections = function() {
var unsubscribes = this._monitoringUnsubscribes.slice(0);
this._monitoringDocuments.length = 0;
this._monitoringUnsubscribes.length = 0;
for (var i = 0; i < unsubscribes.length; i++) {
unsubscribes[i]();
}
};
/**
* 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() {
if (!this.root && crossOriginUpdater && !crossOriginRect) {
// Cross origin monitoring, but no initial data available yet.
return;
}
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, targetRect, rootRect);
var rootBounds = null;
if (!this._rootContainsTarget(target)) {
rootBounds = getEmptyRect();
} else if (!crossOriginUpdater || this.root) {
rootBounds = rootRect;
}
var newEntry = item.entry = new IntersectionObserverEntry({
time: now(),
target: target,
boundingClientRect: targetRect,
rootBounds: rootBounds,
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} targetRect The bounding rect of the target.
* @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, targetRect, rootRect) {
// If the element isn't displayed, an intersection can't happen.
if (window.getComputedStyle(target).display == 'none') return;
var intersectionRect = targetRect;
var parent = getParentNode(target);
var atRoot = false;
while (!atRoot && parent) {
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 null;
if (parent == this.root || parent.nodeType == /* DOCUMENT */ 9) {
atRoot = true;
if (parent == this.root || parent == document) {
if (crossOriginUpdater && !this.root) {
if (!crossOriginRect ||
crossOriginRect.width == 0 && crossOriginRect.height == 0) {
// A 0-size cross-origin intersection means no-intersection.
parent = null;
parentRect = null;
intersectionRect = null;
} else {
parentRect = crossOriginRect;
}
} else {
parentRect = rootRect;
}
} else {
// Check if there's a frame that can be navigated to.
var frame = getParentNode(parent);
var frameRect = frame && getBoundingClientRect(frame);
var frameIntersect =
frame &&
this._computeTargetAndRootIntersection(frame, frameRect, rootRect);
if (frameRect && frameIntersect) {
parent = frame;
parentRect = convertFromParentRect(frameRect, frameIntersect);
} else {
parent = null;
intersectionRect = null;
}
}
} 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.
var doc = parent.ownerDocument;
if (parent != doc.body &&
parent != doc.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 = parent && getParentNode(parent);
}
return intersectionRect;
};
/**
* Returns the root rect after being expanded by the rootMargin value.
* @return {ClientRect} The expanded root rect.
* @private
*/
IntersectionObserver.prototype._getRootRect = function() {
var rootRect;
if (this.root && !isDoc(this.root)) {
rootRect = getBoundingClientRect(this.root);
} else {
// Use <html>/<body> instead of window since scroll bars affect size.
var doc = isDoc(this.root) ? this.root : document;
var html = doc.documentElement;
var body = doc.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 {DOMRect|ClientRect} rect The rect object to expand.
* @return {ClientRect} 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) {
var rootDoc =
(this.root && (this.root.ownerDocument || this.root)) || document;
return (
containsDeep(rootDoc, target) &&
(!this.root || rootDoc == target.ownerDocument)
);
};
/**
* 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|?ClientRect} 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
} || null;
}
/**
* Shims the native getBoundingClientRect for compatibility with older IE.
* @param {Element} el The element whose bounding rect to get.
* @return {DOMRect|ClientRect} 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 {ClientRect} The empty rect.
*/
function getEmptyRect() {
return {
top: 0,
bottom: 0,
left: 0,
right: 0,
width: 0,
height: 0
};
}
/**
* Ensure that the result has all of the necessary fields of the DOMRect.
* Specifically this ensures that `x` and `y` fields are set.
*
* @param {?DOMRect|?ClientRect} rect
* @return {?DOMRect}
*/
function ensureDOMRect(rect) {
// A `DOMRect` object has `x` and `y` fields.
if (!rect || 'x' in rect) {
return rect;
}
// A IE's `ClientRect` type does not have `x` and `y`. The same is the case
// for internally calculated Rect objects. For the purposes of
// `IntersectionObserver`, it's sufficient to simply mirror `left` and `top`
// for these fields.
return {
top: rect.top,
y: rect.top,
bottom: rect.bottom,
left: rect.left,
x: rect.left,
right: rect.right,
width: rect.width,
height: rect.height
};
}
/**
* Inverts the intersection and bounding rect from the parent (frame) BCR to
* the local BCR space.
* @param {DOMRect|ClientRect} parentBoundingRect The parent's bound client rect.
* @param {DOMRect|ClientRect} parentIntersectionRect The parent's own intersection rect.
* @return {ClientRect} The local root bounding rect for the parent's children.
*/
function convertFromParentRect(parentBoundingRect, parentIntersectionRect) {
var top = parentIntersectionRect.top - parentBoundingRect.top;
var left = parentIntersectionRect.left - parentBoundingRect.left;
return {
top: top,
left: left,
height: parentIntersectionRect.height,
width: parentIntersectionRect.width,
bottom: top + parentIntersectionRect.height,
right: left + parentIntersectionRect.width
};
}
/**
* 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 (node.nodeType == /* DOCUMENT */ 9 && node != document) {
// If this node is a document node, look for the embedding frame.
return getFrameElement(node);
}
// If the parent has element that is assigned through shadow root slot
if (parent && parent.assignedSlot) {
parent = parent.assignedSlot.parentNode
}
if (parent && parent.nodeType == 11 && parent.host) {
// If the parent is a shadow root, return the host element.
return parent.host;
}
return parent;
}
/**
* Returns true if `node` is a Document.
* @param {!Node} node
* @returns {boolean}
*/
function isDoc(node) {
return node && node.nodeType === 9;
}
// Exposes the constructors globally.
window.IntersectionObserver = IntersectionObserver;
window.IntersectionObserverEntry = IntersectionObserverEntry;
}());