core/resources/lazyload/intersectionObserver.polyfill.src.js
if (!window.getComputedStyle) {
/**
* @param {(Element|null)} e
* @param {(null|string)=} t
* @return {(CSSStyleDeclaration|null)}
*/
window.getComputedStyle = function(e, t) {
return this.el = e, this.getPropertyValue = function(t) {
/** @type {RegExp} */
var n = /(\-([a-z]){1})/g;
return t == "float" && (t = "styleFloat"), n.test(t) && (t = t.replace(n, function() {
return arguments[2].toUpperCase();
})), e.currentStyle[t] ? e.currentStyle[t] : null;
}, this;
};
}
/*!
* https://github.com/es-shims/es5-shim
* @license es5-shim Copyright 2009-2020 by contributors, MIT License
* see https://github.com/es-shims/es5-shim/blob/master/LICENSE
*/
// vim: ts=4 sts=4 sw=4 expandtab
// Add semicolon to prevent IIFE from being passed as argument to concatenated code.
;
// UMD (Universal Module Definition)
// see https://github.com/umdjs/umd/blob/master/templates/returnExports.js
(function (root, factory) {
'use strict';
/* global define */
if (typeof define === 'function' && define.amd) {
// AMD. Register as an anonymous module.
define(factory);
} else if (typeof exports === 'object') {
// Node. Does not work with strict CommonJS, but
// only CommonJS-like enviroments that support module.exports,
// like Node.
module.exports = factory();
} else {
// Browser globals (root is window)
root.returnExports = factory(); // eslint-disable-line no-param-reassign
}
}(this, function () {
var call = Function.call;
var prototypeOfObject = Object.prototype;
var owns = call.bind(prototypeOfObject.hasOwnProperty);
var isEnumerable = call.bind(prototypeOfObject.propertyIsEnumerable);
var toStr = call.bind(prototypeOfObject.toString);
// If JS engine supports accessors creating shortcuts.
var defineGetter;
var defineSetter;
var lookupGetter;
var lookupSetter;
var supportsAccessors = owns(prototypeOfObject, '__defineGetter__');
if (supportsAccessors) {
/* eslint-disable no-underscore-dangle, no-restricted-properties */
defineGetter = call.bind(prototypeOfObject.__defineGetter__);
defineSetter = call.bind(prototypeOfObject.__defineSetter__);
lookupGetter = call.bind(prototypeOfObject.__lookupGetter__);
lookupSetter = call.bind(prototypeOfObject.__lookupSetter__);
/* eslint-enable no-underscore-dangle, no-restricted-properties */
}
var isPrimitive = function isPrimitive(o) {
return o == null || (typeof o !== 'object' && typeof o !== 'function');
};
// ES5 15.2.3.2
// http://es5.github.com/#x15.2.3.2
if (!Object.getPrototypeOf) {
// https://github.com/es-shims/es5-shim/issues#issue/2
// http://ejohn.org/blog/objectgetprototypeof/
// recommended by fschaefer on github
//
// sure, and webreflection says ^_^
// ... this will nerever possibly return null
// ... Opera Mini breaks here with infinite loops
Object.getPrototypeOf = function getPrototypeOf(object) {
// eslint-disable-next-line no-proto
var proto = object.__proto__;
if (proto || proto === null) {
return proto;
} else if (toStr(object.constructor) === '[object Function]') {
return object.constructor.prototype;
} else if (object instanceof Object) {
return prototypeOfObject;
} else {
// Correctly return null for Objects created with `Object.create(null)`
// (shammed or native) or `{ __proto__: null}`. Also returns null for
// cross-realm objects on browsers that lack `__proto__` support (like
// IE <11), but that's the best we can do.
return null;
}
};
}
// ES5 15.2.3.3
// http://es5.github.com/#x15.2.3.3
// check whether getOwnPropertyDescriptor works if it's given. Otherwise, shim partially.
if (Object.defineProperty) {
var doesGetOwnPropertyDescriptorWork = function doesGetOwnPropertyDescriptorWork(object) {
try {
object.sentinel = 0; // eslint-disable-line no-param-reassign
return Object.getOwnPropertyDescriptor(object, 'sentinel').value === 0;
} catch (exception) {
return false;
}
};
var getOwnPropertyDescriptorWorksOnObject = doesGetOwnPropertyDescriptorWork({});
var getOwnPropertyDescriptorWorksOnDom = typeof document === 'undefined'
|| doesGetOwnPropertyDescriptorWork(document.createElement('div'));
if (!getOwnPropertyDescriptorWorksOnDom || !getOwnPropertyDescriptorWorksOnObject) {
var getOwnPropertyDescriptorFallback = Object.getOwnPropertyDescriptor;
}
}
if (!Object.getOwnPropertyDescriptor || getOwnPropertyDescriptorFallback) {
var ERR_NON_OBJECT = 'Object.getOwnPropertyDescriptor called on a non-object: ';
/* eslint-disable no-proto */
Object.getOwnPropertyDescriptor = function getOwnPropertyDescriptor(object, property) {
if (isPrimitive(object)) {
throw new TypeError(ERR_NON_OBJECT + object);
}
// make a valiant attempt to use the real getOwnPropertyDescriptor
// for I8's DOM elements.
if (getOwnPropertyDescriptorFallback) {
try {
return getOwnPropertyDescriptorFallback.call(Object, object, property);
} catch (exception) {
// try the shim if the real one doesn't work
}
}
var descriptor;
// If object does not owns property return undefined immediately.
if (!owns(object, property)) {
return descriptor;
}
// If object has a property then it's for sure `configurable`, and
// probably `enumerable`. Detect enumerability though.
descriptor = {
enumerable: isEnumerable(object, property),
configurable: true
};
// If JS engine supports accessor properties then property may be a
// getter or setter.
if (supportsAccessors) {
// Unfortunately `__lookupGetter__` will return a getter even
// if object has own non getter property along with a same named
// inherited getter. To avoid misbehavior we temporary remove
// `__proto__` so that `__lookupGetter__` will return getter only
// if it's owned by an object.
var prototype = object.__proto__;
var notPrototypeOfObject = object !== prototypeOfObject;
// avoid recursion problem, breaking in Opera Mini when
// Object.getOwnPropertyDescriptor(Object.prototype, 'toString')
// or any other Object.prototype accessor
if (notPrototypeOfObject) {
object.__proto__ = prototypeOfObject; // eslint-disable-line no-param-reassign
}
var getter = lookupGetter(object, property);
var setter = lookupSetter(object, property);
if (notPrototypeOfObject) {
// Once we have getter and setter we can put values back.
object.__proto__ = prototype; // eslint-disable-line no-param-reassign
}
if (getter || setter) {
if (getter) {
descriptor.get = getter;
}
if (setter) {
descriptor.set = setter;
}
// If it was accessor property we're done and return here
// in order to avoid adding `value` to the descriptor.
return descriptor;
}
}
// If we got this far we know that object has an own property that is
// not an accessor so we set it as a value and return descriptor.
descriptor.value = object[property];
descriptor.writable = true;
return descriptor;
};
/* eslint-enable no-proto */
}
// ES5 15.2.3.4
// http://es5.github.com/#x15.2.3.4
if (!Object.getOwnPropertyNames) {
Object.getOwnPropertyNames = function getOwnPropertyNames(object) {
return Object.keys(object);
};
}
// ES5 15.2.3.5
// http://es5.github.com/#x15.2.3.5
if (!Object.create) {
// Contributed by Brandon Benvie, October, 2012
var createEmpty;
var supportsProto = !({ __proto__: null } instanceof Object);
// the following produces false positives
// in Opera Mini => not a reliable check
// Object.prototype.__proto__ === null
// Check for document.domain and active x support
// No need to use active x approach when document.domain is not set
// see https://github.com/es-shims/es5-shim/issues/150
// variation of https://github.com/kitcambridge/es5-shim/commit/4f738ac066346
/* global ActiveXObject */
var shouldUseActiveX = function shouldUseActiveX() {
// return early if document.domain not set
if (!document.domain) {
return false;
}
try {
return !!new ActiveXObject('htmlfile');
} catch (exception) {
return false;
}
};
// This supports IE8 when document.domain is used
// see https://github.com/es-shims/es5-shim/issues/150
// variation of https://github.com/kitcambridge/es5-shim/commit/4f738ac066346
var getEmptyViaActiveX = function getEmptyViaActiveX() {
var empty;
var xDoc;
xDoc = new ActiveXObject('htmlfile');
var script = 'script';
xDoc.write('<' + script + '></' + script + '>');
xDoc.close();
empty = xDoc.parentWindow.Object.prototype;
xDoc = null;
return empty;
};
// The original implementation using an iframe
// before the activex approach was added
// see https://github.com/es-shims/es5-shim/issues/150
var getEmptyViaIFrame = function getEmptyViaIFrame() {
var iframe = document.createElement('iframe');
var parent = document.body || document.documentElement;
var empty;
iframe.style.display = 'none';
parent.appendChild(iframe);
// eslint-disable-next-line no-script-url
iframe.src = 'javascript:';
empty = iframe.contentWindow.Object.prototype;
parent.removeChild(iframe);
iframe = null;
return empty;
};
/* global document */
if (supportsProto || typeof document === 'undefined') {
createEmpty = function () {
return { __proto__: null };
};
} else {
// In old IE __proto__ can't be used to manually set `null`, nor does
// any other method exist to make an object that inherits from nothing,
// aside from Object.prototype itself. Instead, create a new global
// object and *steal* its Object.prototype and strip it bare. This is
// used as the prototype to create nullary objects.
createEmpty = function () {
// Determine which approach to use
// see https://github.com/es-shims/es5-shim/issues/150
var empty = shouldUseActiveX() ? getEmptyViaActiveX() : getEmptyViaIFrame();
delete empty.constructor;
delete empty.hasOwnProperty;
delete empty.propertyIsEnumerable;
delete empty.isPrototypeOf;
delete empty.toLocaleString;
delete empty.toString;
delete empty.valueOf;
var Empty = function Empty() {};
Empty.prototype = empty;
// short-circuit future calls
createEmpty = function () {
return new Empty();
};
return new Empty();
};
}
Object.create = function create(prototype, properties) {
var object;
var Type = function Type() {}; // An empty constructor.
if (prototype === null) {
object = createEmpty();
} else if (isPrimitive(prototype)) {
// In the native implementation `parent` can be `null`
// OR *any* `instanceof Object` (Object|Function|Array|RegExp|etc)
// Use `typeof` tho, b/c in old IE, DOM elements are not `instanceof Object`
// like they are in modern browsers. Using `Object.create` on DOM elements
// is...err...probably inappropriate, but the native version allows for it.
throw new TypeError('Object prototype may only be an Object or null'); // same msg as Chrome
} else {
Type.prototype = prototype;
object = new Type();
// IE has no built-in implementation of `Object.getPrototypeOf`
// neither `__proto__`, but this manually setting `__proto__` will
// guarantee that `Object.getPrototypeOf` will work as expected with
// objects created using `Object.create`
// eslint-disable-next-line no-proto
object.__proto__ = prototype;
}
if (properties !== void 0) {
Object.defineProperties(object, properties);
}
return object;
};
}
// ES5 15.2.3.6
// http://es5.github.com/#x15.2.3.6
// Patch for WebKit and IE8 standard mode
// Designed by hax <hax.github.com>
// related issue: https://github.com/es-shims/es5-shim/issues#issue/5
// IE8 Reference:
// http://msdn.microsoft.com/en-us/library/dd282900.aspx
// http://msdn.microsoft.com/en-us/library/dd229916.aspx
// WebKit Bugs:
// https://bugs.webkit.org/show_bug.cgi?id=36423
var doesDefinePropertyWork = function doesDefinePropertyWork(object) {
try {
Object.defineProperty(object, 'sentinel', {});
return 'sentinel' in object;
} catch (exception) {
return false;
}
};
// check whether defineProperty works if it's given. Otherwise,
// shim partially.
if (Object.defineProperty) {
var definePropertyWorksOnObject = doesDefinePropertyWork({});
var definePropertyWorksOnDom = typeof document === 'undefined'
|| doesDefinePropertyWork(document.createElement('div'));
if (!definePropertyWorksOnObject || !definePropertyWorksOnDom) {
var definePropertyFallback = Object.defineProperty,
definePropertiesFallback = Object.defineProperties;
}
}
if (!Object.defineProperty || definePropertyFallback) {
var ERR_NON_OBJECT_DESCRIPTOR = 'Property description must be an object: ';
var ERR_NON_OBJECT_TARGET = 'Object.defineProperty called on non-object: ';
var ERR_ACCESSORS_NOT_SUPPORTED = 'getters & setters can not be defined on this javascript engine';
Object.defineProperty = function defineProperty(object, property, descriptor) {
if (isPrimitive(object)) {
throw new TypeError(ERR_NON_OBJECT_TARGET + object);
}
if (isPrimitive(descriptor)) {
throw new TypeError(ERR_NON_OBJECT_DESCRIPTOR + descriptor);
}
// make a valiant attempt to use the real defineProperty
// for I8's DOM elements.
if (definePropertyFallback) {
try {
return definePropertyFallback.call(Object, object, property, descriptor);
} catch (exception) {
// try the shim if the real one doesn't work
}
}
// If it's a data property.
if ('value' in descriptor) {
// fail silently if 'writable', 'enumerable', or 'configurable'
// are requested but not supported
/*
// alternate approach:
if ( // can't implement these features; allow false but not true
('writable' in descriptor && !descriptor.writable) ||
('enumerable' in descriptor && !descriptor.enumerable) ||
('configurable' in descriptor && !descriptor.configurable)
))
throw new RangeError(
'This implementation of Object.defineProperty does not support configurable, enumerable, or writable.'
);
*/
if (supportsAccessors && (lookupGetter(object, property) || lookupSetter(object, property))) {
// As accessors are supported only on engines implementing
// `__proto__` we can safely override `__proto__` while defining
// a property to make sure that we don't hit an inherited
// accessor.
/* eslint-disable no-proto, no-param-reassign */
var prototype = object.__proto__;
object.__proto__ = prototypeOfObject;
// Deleting a property anyway since getter / setter may be
// defined on object itself.
delete object[property];
object[property] = descriptor.value;
// Setting original `__proto__` back now.
object.__proto__ = prototype;
/* eslint-enable no-proto, no-param-reassign */
} else {
object[property] = descriptor.value; // eslint-disable-line no-param-reassign
}
} else {
var hasGetter = 'get' in descriptor;
var hasSetter = 'set' in descriptor;
if (!supportsAccessors && (hasGetter || hasSetter)) {
throw new TypeError(ERR_ACCESSORS_NOT_SUPPORTED);
}
// If we got that far then getters and setters can be defined !!
if (hasGetter) {
defineGetter(object, property, descriptor.get);
}
if (hasSetter) {
defineSetter(object, property, descriptor.set);
}
}
return object;
};
}
// ES5 15.2.3.7
// http://es5.github.com/#x15.2.3.7
if (!Object.defineProperties || definePropertiesFallback) {
Object.defineProperties = function defineProperties(object, properties) {
// make a valiant attempt to use the real defineProperties
if (definePropertiesFallback) {
try {
return definePropertiesFallback.call(Object, object, properties);
} catch (exception) {
// try the shim if the real one doesn't work
}
}
Object.keys(properties).forEach(function (property) {
if (property !== '__proto__') {
Object.defineProperty(object, property, properties[property]);
}
});
return object;
};
}
// ES5 15.2.3.8
// http://es5.github.com/#x15.2.3.8
if (!Object.seal) {
Object.seal = function seal(object) {
if (Object(object) !== object) {
throw new TypeError('Object.seal can only be called on Objects.');
}
// this is misleading and breaks feature-detection, but
// allows "securable" code to "gracefully" degrade to working
// but insecure code.
return object;
};
}
// ES5 15.2.3.9
// http://es5.github.com/#x15.2.3.9
if (!Object.freeze) {
Object.freeze = function freeze(object) {
if (Object(object) !== object) {
throw new TypeError('Object.freeze can only be called on Objects.');
}
// this is misleading and breaks feature-detection, but
// allows "securable" code to "gracefully" degrade to working
// but insecure code.
return object;
};
}
// detect a Rhino bug and patch it
try {
Object.freeze(function () {});
} catch (exception) {
Object.freeze = (function (freezeObject) {
return function freeze(object) {
if (typeof object === 'function') {
return object;
} else {
return freezeObject(object);
}
};
}(Object.freeze));
}
// ES5 15.2.3.10
// http://es5.github.com/#x15.2.3.10
if (!Object.preventExtensions) {
Object.preventExtensions = function preventExtensions(object) {
if (Object(object) !== object) {
throw new TypeError('Object.preventExtensions can only be called on Objects.');
}
// this is misleading and breaks feature-detection, but
// allows "securable" code to "gracefully" degrade to working
// but insecure code.
return object;
};
}
// ES5 15.2.3.11
// http://es5.github.com/#x15.2.3.11
if (!Object.isSealed) {
Object.isSealed = function isSealed(object) {
if (Object(object) !== object) {
throw new TypeError('Object.isSealed can only be called on Objects.');
}
return false;
};
}
// ES5 15.2.3.12
// http://es5.github.com/#x15.2.3.12
if (!Object.isFrozen) {
Object.isFrozen = function isFrozen(object) {
if (Object(object) !== object) {
throw new TypeError('Object.isFrozen can only be called on Objects.');
}
return false;
};
}
// ES5 15.2.3.13
// http://es5.github.com/#x15.2.3.13
if (!Object.isExtensible) {
Object.isExtensible = function isExtensible(object) {
// 1. If Type(O) is not Object throw a TypeError exception.
if (Object(object) !== object) {
throw new TypeError('Object.isExtensible can only be called on Objects.');
}
// 2. Return the Boolean value of the [[Extensible]] internal property of O.
var name = '';
while (owns(object, name)) {
name += '?';
}
object[name] = true; // eslint-disable-line no-param-reassign
var returnValue = owns(object, name);
delete object[name]; // eslint-disable-line no-param-reassign
return returnValue;
};
}
}));
/**
* 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) {
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(' ');
/** @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.
if (doc != (this.root && this.root.ownerDocument || document)) {
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 || 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 newEntry = item.entry = new IntersectionObserverEntry({
time: now(),
target: target,
boundingClientRect: targetRect,
rootBounds: crossOriginUpdater && !this.root ? null : 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} 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) {
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 {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) {
return containsDeep(this.root || document, target) &&
(!this.root || this.root.ownerDocument == 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 (parent && parent.nodeType == 11 && parent.host) {
// If the parent is a shadow root, return the host element.
return parent.host;
}
if (parent && parent.assignedSlot) {
// If the parent is distributed in a <slot>, return the parent of a slot.
return parent.assignedSlot.parentNode;
}
return parent;
}
// Exposes the constructors globally.
window.IntersectionObserver = IntersectionObserver;
window.IntersectionObserverEntry = IntersectionObserverEntry;
}());