(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? module.exports = factory() :
typeof define === 'function' && define.amd ? define(factory) :
(global.ResizeObserver = factory());
}(this, (function () { 'use strict';
/**
* A collection of shims that provide minimal functionality of the ES6 collections.
*
* These implementations are not meant to be used outside of the ResizeObserver
* modules as they cover only a limited range of use cases.
*/
/* eslint-disable require-jsdoc, valid-jsdoc */
var MapShim = (function () {
if (typeof Map !== 'undefined') {
return Map;
}
/**
* Returns index in provided array that matches the specified key.
*
* @param {Array<Array>} arr
* @param {*} key
* @returns {number}
*/
function getIndex(arr, key) {
var result = -1;
arr.some(function (entry, index) {
if (entry[0] === key) {
result = index;
return true;
}
return false;
});
return result;
}
return /** @class */ (function () {
function class_1() {
this.__entries__ = [];
}
Object.defineProperty(class_1.prototype, "size", {
/**
* @returns {boolean}
*/
get: function () {
return this.__entries__.length;
},
enumerable: true,
configurable: true
});
/**
* @param {*} key
* @returns {*}
*/
class_1.prototype.get = function (key) {
var index = getIndex(this.__entries__, key);
var entry = this.__entries__[index];
return entry && entry[1];
};
/**
* @param {*} key
* @param {*} value
* @returns {void}
*/
class_1.prototype.set = function (key, value) {
var index = getIndex(this.__entries__, key);
if (~index) {
this.__entries__[index][1] = value;
}
else {
this.__entries__.push([key, value]);
}
};
/**
* @param {*} key
* @returns {void}
*/
class_1.prototype.delete = function (key) {
var entries = this.__entries__;
var index = getIndex(entries, key);
if (~index) {
entries.splice(index, 1);
}
};
/**
* @param {*} key
* @returns {void}
*/
class_1.prototype.has = function (key) {
return !!~getIndex(this.__entries__, key);
};
/**
* @returns {void}
*/
class_1.prototype.clear = function () {
this.__entries__.splice(0);
};
/**
* @param {Function} callback
* @param {*} [ctx=null]
* @returns {void}
*/
class_1.prototype.forEach = function (callback, ctx) {
if (ctx === void 0) { ctx = null; }
for (var _i = 0, _a = this.__entries__; _i < _a.length; _i++) {
var entry = _a[_i];
callback.call(ctx, entry[1], entry[0]);
}
};
return class_1;
}());
})();
/**
* Detects whether window and document objects are available in current environment.
*/
var isBrowser = typeof window !== 'undefined' && typeof document !== 'undefined' && window.document === document;
// Returns global object of a current environment.
var global$1 = (function () {
if (typeof global !== 'undefined' && global.Math === Math) {
return global;
}
if (typeof self !== 'undefined' && self.Math === Math) {
return self;
}
if (typeof window !== 'undefined' && window.Math === Math) {
return window;
}
// eslint-disable-next-line no-new-func
return Function('return this')();
})();
/**
* A shim for the requestAnimationFrame which falls back to the setTimeout if
* first one is not supported.
*
* @returns {number} Requests' identifier.
*/
var requestAnimationFrame$1 = (function () {
if (typeof requestAnimationFrame === 'function') {
// It's required to use a bounded function because IE sometimes throws
// an "Invalid calling object" error if rAF is invoked without the global
// object on the left hand side.
return requestAnimationFrame.bind(global$1);
}
return function (callback) { return setTimeout(function () { return callback(Date.now()); }, 1000 / 60); };
})();
// Defines minimum timeout before adding a trailing call.
var trailingTimeout = 2;
/**
* Creates a wrapper function which ensures that provided callback will be
* invoked only once during the specified delay period.
*
* @param {Function} callback - Function to be invoked after the delay period.
* @param {number} delay - Delay after which to invoke callback.
* @returns {Function}
*/
function throttle (callback, delay) {
var leadingCall = false, trailingCall = false, lastCallTime = 0;
/**
* Invokes the original callback function and schedules new invocation if
* the "proxy" was called during current request.
*
* @returns {void}
*/
function resolvePending() {
if (leadingCall) {
leadingCall = false;
callback();
}
if (trailingCall) {
proxy();
}
}
/**
* Callback invoked after the specified delay. It will further postpone
* invocation of the original function delegating it to the
* requestAnimationFrame.
*
* @returns {void}
*/
function timeoutCallback() {
requestAnimationFrame$1(resolvePending);
}
/**
* Schedules invocation of the original function.
*
* @returns {void}
*/
function proxy() {
var timeStamp = Date.now();
if (leadingCall) {
// Reject immediately following calls.
if (timeStamp - lastCallTime < trailingTimeout) {
return;
}
// Schedule new call to be in invoked when the pending one is resolved.
// This is important for "transitions" which never actually start
// immediately so there is a chance that we might miss one if change
// happens amids the pending invocation.
trailingCall = true;
}
else {
leadingCall = true;
trailingCall = false;
setTimeout(timeoutCallback, delay);
}
lastCallTime = timeStamp;
}
return proxy;
}
// Minimum delay before invoking the update of observers.
var REFRESH_DELAY = 20;
// A list of substrings of CSS properties used to find transition events that
// might affect dimensions of observed elements.
var transitionKeys = ['top', 'right', 'bottom', 'left', 'width', 'height', 'size', 'weight'];
// Check if MutationObserver is available.
var mutationObserverSupported = typeof MutationObserver !== 'undefined';
/**
* Singleton controller class which handles updates of ResizeObserver instances.
*/
var ResizeObserverController = /** @class */ (function () {
/**
* Creates a new instance of ResizeObserverController.
*
* @private
*/
function ResizeObserverController() {
/**
* Indicates whether DOM listeners have been added.
*
* @private {boolean}
*/
this.connected_ = false;
/**
* Tells that controller has subscribed for Mutation Events.
*
* @private {boolean}
*/
this.mutationEventsAdded_ = false;
/**
* Keeps reference to the instance of MutationObserver.
*
* @private {MutationObserver}
*/
this.mutationsObserver_ = null;
/**
* A list of connected observers.
*
* @private {Array<ResizeObserverSPI>}
*/
this.observers_ = [];
this.onTransitionEnd_ = this.onTransitionEnd_.bind(this);
this.refresh = throttle(this.refresh.bind(this), REFRESH_DELAY);
}
/**
* Adds observer to observers list.
*
* @param {ResizeObserverSPI} observer - Observer to be added.
* @returns {void}
*/
ResizeObserverController.prototype.addObserver = function (observer) {
if (!~this.observers_.indexOf(observer)) {
this.observers_.push(observer);
}
// Add listeners if they haven't been added yet.
if (!this.connected_) {
this.connect_();
}
};
/**
* Removes observer from observers list.
*
* @param {ResizeObserverSPI} observer - Observer to be removed.
* @returns {void}
*/
ResizeObserverController.prototype.removeObserver = function (observer) {
var observers = this.observers_;
var index = observers.indexOf(observer);
// Remove observer if it's present in registry.
if (~index) {
observers.splice(index, 1);
}
// Remove listeners if controller has no connected observers.
if (!observers.length && this.connected_) {
this.disconnect_();
}
};
/**
* Invokes the update of observers. It will continue running updates insofar
* it detects changes.
*
* @returns {void}
*/
ResizeObserverController.prototype.refresh = function () {
var changesDetected = this.updateObservers_();
// Continue running updates if changes have been detected as there might
// be future ones caused by CSS transitions.
if (changesDetected) {
this.refresh();
}
};
/**
* Updates every observer from observers list and notifies them of queued
* entries.
*
* @private
* @returns {boolean} Returns "true" if any observer has detected changes in
* dimensions of it's elements.
*/
ResizeObserverController.prototype.updateObservers_ = function () {
// Collect observers that have active observations.
var activeObservers = this.observers_.filter(function (observer) {
return observer.gatherActive(), observer.hasActive();
});
// Deliver notifications in a separate cycle in order to avoid any
// collisions between observers, e.g. when multiple instances of
// ResizeObserver are tracking the same element and the callback of one
// of them changes content dimensions of the observed target. Sometimes
// this may result in notifications being blocked for the rest of observers.
activeObservers.forEach(function (observer) { return observer.broadcastActive(); });
return activeObservers.length > 0;
};
/**
* Initializes DOM listeners.
*
* @private
* @returns {void}
*/
ResizeObserverController.prototype.connect_ = function () {
// Do nothing if running in a non-browser environment or if listeners
// have been already added.
if (!isBrowser || this.connected_) {
return;
}
// Subscription to the "Transitionend" event is used as a workaround for
// delayed transitions. This way it's possible to capture at least the
// final state of an element.
document.addEventListener('transitionend', this.onTransitionEnd_);
window.addEventListener('resize', this.refresh);
if (mutationObserverSupported) {
this.mutationsObserver_ = new MutationObserver(this.refresh);
this.mutationsObserver_.observe(document, {
attributes: true,
childList: true,
characterData: true,
subtree: true
});
}
else {
document.addEventListener('DOMSubtreeModified', this.refresh);
this.mutationEventsAdded_ = true;
}
this.connected_ = true;
};
/**
* Removes DOM listeners.
*
* @private
* @returns {void}
*/
ResizeObserverController.prototype.disconnect_ = function () {
// Do nothing if running in a non-browser environment or if listeners
// have been already removed.
if (!isBrowser || !this.connected_) {
return;
}
document.removeEventListener('transitionend', this.onTransitionEnd_);
window.removeEventListener('resize', this.refresh);
if (this.mutationsObserver_) {
this.mutationsObserver_.disconnect();
}
if (this.mutationEventsAdded_) {
document.removeEventListener('DOMSubtreeModified', this.refresh);
}
this.mutationsObserver_ = null;
this.mutationEventsAdded_ = false;
this.connected_ = false;
};
/**
* "Transitionend" event handler.
*
* @private
* @param {TransitionEvent} event
* @returns {void}
*/
ResizeObserverController.prototype.onTransitionEnd_ = function (_a) {
var _b = _a.propertyName, propertyName = _b === void 0 ? '' : _b;
// Detect whether transition may affect dimensions of an element.
var isReflowProperty = transitionKeys.some(function (key) {
return !!~propertyName.indexOf(key);
});
if (isReflowProperty) {
this.refresh();
}
};
/**
* Returns instance of the ResizeObserverController.
*
* @returns {ResizeObserverController}
*/
ResizeObserverController.getInstance = function () {
if (!this.instance_) {
this.instance_ = new ResizeObserverController();
}
return this.instance_;
};
/**
* Holds reference to the controller's instance.
*
* @private {ResizeObserverController}
*/
ResizeObserverController.instance_ = null;
return ResizeObserverController;
}());
/**
* Defines non-writable/enumerable properties of the provided target object.
*
* @param {Object} target - Object for which to define properties.
* @param {Object} props - Properties to be defined.
* @returns {Object} Target object.
*/
var defineConfigurable = (function (target, props) {
for (var _i = 0, _a = Object.keys(props); _i < _a.length; _i++) {
var key = _a[_i];
Object.defineProperty(target, key, {
value: props[key],
enumerable: false,
writable: false,
configurable: true
});
}
return target;
});
/**
* Returns the global object associated with provided element.
*
* @param {Object} target
* @returns {Object}
*/
var getWindowOf = (function (target) {
// Assume that the element is an instance of Node, which means that it
// has the "ownerDocument" property from which we can retrieve a
// corresponding global object.
var ownerGlobal = target && target.ownerDocument && target.ownerDocument.defaultView;
// Return the local global object if it's not possible extract one from
// provided element.
return ownerGlobal || global$1;
});
// Placeholder of an empty content rectangle.
var emptyRect = createRectInit(0, 0, 0, 0);
/**
* Converts provided string to a number.
*
* @param {number|string} value
* @returns {number}
*/
function toFloat(value) {
return parseFloat(value) || 0;
}
/**
* Extracts borders size from provided styles.
*
* @param {CSSStyleDeclaration} styles
* @param {...string} positions - Borders positions (top, right, ...)
* @returns {number}
*/
function getBordersSize(styles) {
var positions = [];
for (var _i = 1; _i < arguments.length; _i++) {
positions[_i - 1] = arguments[_i];
}
return positions.reduce(function (size, position) {
var value = styles['border-' + position + '-width'];
return size + toFloat(value);
}, 0);
}
/**
* Extracts paddings sizes from provided styles.
*
* @param {CSSStyleDeclaration} styles
* @returns {Object} Paddings box.
*/
function getPaddings(styles) {
var positions = ['top', 'right', 'bottom', 'left'];
var paddings = {};
for (var _i = 0, positions_1 = positions; _i < positions_1.length; _i++) {
var position = positions_1[_i];
var value = styles['padding-' + position];
paddings[position] = toFloat(value);
}
return paddings;
}
/**
* Calculates content rectangle of provided SVG element.
*
* @param {SVGGraphicsElement} target - Element content rectangle of which needs
* to be calculated.
* @returns {DOMRectInit}
*/
function getSVGContentRect(target) {
var bbox = target.getBBox();
return createRectInit(0, 0, bbox.width, bbox.height);
}
/**
* Calculates content rectangle of provided HTMLElement.
*
* @param {HTMLElement} target - Element for which to calculate the content rectangle.
* @returns {DOMRectInit}
*/
function getHTMLElementContentRect(target) {
// Client width & height properties can't be
// used exclusively as they provide rounded values.
var clientWidth = target.clientWidth, clientHeight = target.clientHeight;
// By this condition we can catch all non-replaced inline, hidden and
// detached elements. Though elements with width & height properties less
// than 0.5 will be discarded as well.
//
// Without it we would need to implement separate methods for each of
// those cases and it's not possible to perform a precise and performance
// effective test for hidden elements. E.g. even jQuery's ':visible' filter
// gives wrong results for elements with width & height less than 0.5.
if (!clientWidth && !clientHeight) {
return emptyRect;
}
var styles = getWindowOf(target).getComputedStyle(target);
var paddings = getPaddings(styles);
var horizPad = paddings.left + paddings.right;
var vertPad = paddings.top + paddings.bottom;
// Computed styles of width & height are being used because they are the
// only dimensions available to JS that contain non-rounded values. It could
// be possible to utilize the getBoundingClientRect if only it's data wasn't
// affected by CSS transformations let alone paddings, borders and scroll bars.
var width = toFloat(styles.width), height = toFloat(styles.height);
// Width & height include paddings and borders when the 'border-box' box
// model is applied (except for IE).
if (styles.boxSizing === 'border-box') {
// Following conditions are required to handle Internet Explorer which
// doesn't include paddings and borders to computed CSS dimensions.
//
// We can say that if CSS dimensions + paddings are equal to the "client"
// properties then it's either IE, and thus we don't need to subtract
// anything, or an element merely doesn't have paddings/borders styles.
if (Math.round(width + horizPad) !== clientWidth) {
width -= getBordersSize(styles, 'left', 'right') + horizPad;
}
if (Math.round(height + vertPad) !== clientHeight) {
height -= getBordersSize(styles, 'top', 'bottom') + vertPad;
}
}
// Following steps can't be applied to the document's root element as its
// client[Width/Height] properties represent viewport area of the window.
// Besides, it's as well not necessary as the <html> itself neither has
// rendered scroll bars nor it can be clipped.
if (!isDocumentElement(target)) {
// In some browsers (only in Firefox, actually) CSS width & height
// include scroll bars size which can be removed at this step as scroll
// bars are the only difference between rounded dimensions + paddings
// and "client" properties, though that is not always true in Chrome.
var vertScrollbar = Math.round(width + horizPad) - clientWidth;
var horizScrollbar = Math.round(height + vertPad) - clientHeight;
// Chrome has a rather weird rounding of "client" properties.
// E.g. for an element with content width of 314.2px it sometimes gives
// the client width of 315px and for the width of 314.7px it may give
// 314px. And it doesn't happen all the time. So just ignore this delta
// as a non-relevant.
if (Math.abs(vertScrollbar) !== 1) {
width -= vertScrollbar;
}
if (Math.abs(horizScrollbar) !== 1) {
height -= horizScrollbar;
}
}
return createRectInit(paddings.left, paddings.top, width, height);
}
/**
* Checks whether provided element is an instance of the SVGGraphicsElement.
*
* @param {Element} target - Element to be checked.
* @returns {boolean}
*/
var isSVGGraphicsElement = (function () {
// Some browsers, namely IE and Edge, don't have the SVGGraphicsElement
// interface.
if (typeof SVGGraphicsElement !== 'undefined') {
return function (target) { return target instanceof getWindowOf(target).SVGGraphicsElement; };
}
// If it's so, then check that element is at least an instance of the
// SVGElement and that it has the "getBBox" method.
// eslint-disable-next-line no-extra-parens
return function (target) { return (target instanceof getWindowOf(target).SVGElement &&
typeof target.getBBox === 'function'); };
})();
/**
* Checks whether provided element is a document element (<html>).
*
* @param {Element} target - Element to be checked.
* @returns {boolean}
*/
function isDocumentElement(target) {
return target === getWindowOf(target).document.documentElement;
}
/**
* Calculates an appropriate content rectangle for provided html or svg element.
*
* @param {Element} target - Element content rectangle of which needs to be calculated.
* @returns {DOMRectInit}
*/
function getContentRect(target) {
if (!isBrowser) {
return emptyRect;
}
if (isSVGGraphicsElement(target)) {
return getSVGContentRect(target);
}
return getHTMLElementContentRect(target);
}
/**
* Creates rectangle with an interface of the DOMRectReadOnly.
* Spec: https://drafts.fxtf.org/geometry/#domrectreadonly
*
* @param {DOMRectInit} rectInit - Object with rectangle's x/y coordinates and dimensions.
* @returns {DOMRectReadOnly}
*/
function createReadOnlyRect(_a) {
var x = _a.x, y = _a.y, width = _a.width, height = _a.height;
// If DOMRectReadOnly is available use it as a prototype for the rectangle.
var Constr = typeof DOMRectReadOnly !== 'undefined' ? DOMRectReadOnly : Object;
var rect = Object.create(Constr.prototype);
// Rectangle's properties are not writable and non-enumerable.
defineConfigurable(rect, {
x: x, y: y, width: width, height: height,
top: y,
right: x + width,
bottom: height + y,
left: x
});
return rect;
}
/**
* Creates DOMRectInit object based on the provided dimensions and the x/y coordinates.
* Spec: https://drafts.fxtf.org/geometry/#dictdef-domrectinit
*
* @param {number} x - X coordinate.
* @param {number} y - Y coordinate.
* @param {number} width - Rectangle's width.
* @param {number} height - Rectangle's height.
* @returns {DOMRectInit}
*/
function createRectInit(x, y, width, height) {
return { x: x, y: y, width: width, height: height };
}
/**
* Class that is responsible for computations of the content rectangle of
* provided DOM element and for keeping track of it's changes.
*/
var ResizeObservation = /** @class */ (function () {
/**
* Creates an instance of ResizeObservation.
*
* @param {Element} target - Element to be observed.
*/
function ResizeObservation(target) {
/**
* Broadcasted width of content rectangle.
*
* @type {number}
*/
this.broadcastWidth = 0;
/**
* Broadcasted height of content rectangle.
*
* @type {number}
*/
this.broadcastHeight = 0;
/**
* Reference to the last observed content rectangle.
*
* @private {DOMRectInit}
*/
this.contentRect_ = createRectInit(0, 0, 0, 0);
this.target = target;
}
/**
* Updates content rectangle and tells whether it's width or height properties
* have changed since the last broadcast.
*
* @returns {boolean}
*/
ResizeObservation.prototype.isActive = function () {
var rect = getContentRect(this.target);
this.contentRect_ = rect;
return (rect.width !== this.broadcastWidth ||
rect.height !== this.broadcastHeight);
};
/**
* Updates 'broadcastWidth' and 'broadcastHeight' properties with a data
* from the corresponding properties of the last observed content rectangle.
*
* @returns {DOMRectInit} Last observed content rectangle.
*/
ResizeObservation.prototype.broadcastRect = function () {
var rect = this.contentRect_;
this.broadcastWidth = rect.width;
this.broadcastHeight = rect.height;
return rect;
};
return ResizeObservation;
}());
var ResizeObserverEntry = /** @class */ (function () {
/**
* Creates an instance of ResizeObserverEntry.
*
* @param {Element} target - Element that is being observed.
* @param {DOMRectInit} rectInit - Data of the element's content rectangle.
*/
function ResizeObserverEntry(target, rectInit) {
var contentRect = createReadOnlyRect(rectInit);
// According to the specification following properties are not writable
// and are also not enumerable in the native implementation.
//
// Property accessors are not being used as they'd require to define a
// private WeakMap storage which may cause memory leaks in browsers that
// don't support this type of collections.
defineConfigurable(this, { target: target, contentRect: contentRect });
}
return ResizeObserverEntry;
}());
var ResizeObserverSPI = /** @class */ (function () {
/**
* Creates a new instance of ResizeObserver.
*
* @param {ResizeObserverCallback} callback - Callback function that is invoked
* when one of the observed elements changes it's content dimensions.
* @param {ResizeObserverController} controller - Controller instance which
* is responsible for the updates of observer.
* @param {ResizeObserver} callbackCtx - Reference to the public
* ResizeObserver instance which will be passed to callback function.
*/
function ResizeObserverSPI(callback, controller, callbackCtx) {
/**
* Collection of resize observations that have detected changes in dimensions
* of elements.
*
* @private {Array<ResizeObservation>}
*/
this.activeObservations_ = [];
/**
* Registry of the ResizeObservation instances.
*
* @private {Map<Element, ResizeObservation>}
*/
this.observations_ = new MapShim();
if (typeof callback !== 'function') {
throw new TypeError('The callback provided as parameter 1 is not a function.');
}
this.callback_ = callback;
this.controller_ = controller;
this.callbackCtx_ = callbackCtx;
}
/**
* Starts observing provided element.
*
* @param {Element} target - Element to be observed.
* @returns {void}
*/
ResizeObserverSPI.prototype.observe = function (target) {
if (!arguments.length) {
throw new TypeError('1 argument required, but only 0 present.');
}
// Do nothing if current environment doesn't have the Element interface.
if (typeof Element === 'undefined' || !(Element instanceof Object)) {
return;
}
if (!(target instanceof getWindowOf(target).Element)) {
throw new TypeError('parameter 1 is not of type "Element".');
}
var observations = this.observations_;
// Do nothing if element is already being observed.
if (observations.has(target)) {
return;
}
observations.set(target, new ResizeObservation(target));
this.controller_.addObserver(this);
// Force the update of observations.
this.controller_.refresh();
};
/**
* Stops observing provided element.
*
* @param {Element} target - Element to stop observing.
* @returns {void}
*/
ResizeObserverSPI.prototype.unobserve = function (target) {
if (!arguments.length) {
throw new TypeError('1 argument required, but only 0 present.');
}
// Do nothing if current environment doesn't have the Element interface.
if (typeof Element === 'undefined' || !(Element instanceof Object)) {
return;
}
if (!(target instanceof getWindowOf(target).Element)) {
throw new TypeError('parameter 1 is not of type "Element".');
}
var observations = this.observations_;
// Do nothing if element is not being observed.
if (!observations.has(target)) {
return;
}
observations.delete(target);
if (!observations.size) {
this.controller_.removeObserver(this);
}
};
/**
* Stops observing all elements.
*
* @returns {void}
*/
ResizeObserverSPI.prototype.disconnect = function () {
this.clearActive();
this.observations_.clear();
this.controller_.removeObserver(this);
};
/**
* Collects observation instances the associated element of which has changed
* it's content rectangle.
*
* @returns {void}
*/
ResizeObserverSPI.prototype.gatherActive = function () {
var _this = this;
this.clearActive();
this.observations_.forEach(function (observation) {
if (observation.isActive()) {
_this.activeObservations_.push(observation);
}
});
};
/**
* Invokes initial callback function with a list of ResizeObserverEntry
* instances collected from active resize observations.
*
* @returns {void}
*/
ResizeObserverSPI.prototype.broadcastActive = function () {
// Do nothing if observer doesn't have active observations.
if (!this.hasActive()) {
return;
}
var ctx = this.callbackCtx_;
// Create ResizeObserverEntry instance for every active observation.
var entries = this.activeObservations_.map(function (observation) {
return new ResizeObserverEntry(observation.target, observation.broadcastRect());
});
this.callback_.call(ctx, entries, ctx);
this.clearActive();
};
/**
* Clears the collection of active observations.
*
* @returns {void}
*/
ResizeObserverSPI.prototype.clearActive = function () {
this.activeObservations_.splice(0);
};
/**
* Tells whether observer has active observations.
*
* @returns {boolean}
*/
ResizeObserverSPI.prototype.hasActive = function () {
return this.activeObservations_.length > 0;
};
return ResizeObserverSPI;
}());
// Registry of internal observers. If WeakMap is not available use current shim
// for the Map collection as it has all required methods and because WeakMap
// can't be fully polyfilled anyway.
var observers = typeof WeakMap !== 'undefined' ? new WeakMap() : new MapShim();
/**
* ResizeObserver API. Encapsulates the ResizeObserver SPI implementation
* exposing only those methods and properties that are defined in the spec.
*/
var ResizeObserver = /** @class */ (function () {
/**
* Creates a new instance of ResizeObserver.
*
* @param {ResizeObserverCallback} callback - Callback that is invoked when
* dimensions of the observed elements change.
*/
function ResizeObserver(callback) {
if (!(this instanceof ResizeObserver)) {
throw new TypeError('Cannot call a class as a function.');
}
if (!arguments.length) {
throw new TypeError('1 argument required, but only 0 present.');
}
var controller = ResizeObserverController.getInstance();
var observer = new ResizeObserverSPI(callback, controller, this);
observers.set(this, observer);
}
return ResizeObserver;
}());
// Expose public methods of ResizeObserver.
[
'observe',
'unobserve',
'disconnect'
].forEach(function (method) {
ResizeObserver.prototype[method] = function () {
var _a;
return (_a = observers.get(this))[method].apply(_a, arguments);
};
});
var index = (function () {
// Export existing implementation if available.
if (typeof global$1.ResizeObserver !== 'undefined') {
return global$1.ResizeObserver;
}
return ResizeObserver;
})();
return index;
})));