> // or element, update the intersection rect. // Note:
and cannot be clipped to a rect that's not also // the document rect, so no need to compute a new intersection. if (parent != document.body && parent != document.documentElement && parentComputedStyle.overflow != 'visible') { parentRect = getBoundingClientRect(parent); } } // If either of the above conditionals set a new parentRect, // calculate new intersection data. if (parentRect) { intersectionRect = computeRectIntersection(parentRect, intersectionRect); if (!intersectionRect) break; } parent = getParentNode(parent); } return intersectionRect; }; /** * Returns the root rect after being expanded by the rootMargin value. * @return {Object} The expanded root rect. * @private */ IntersectionObserver.prototype._getRootRect = function() { var rootRect; if (this.root) { rootRect = getBoundingClientRect(this.root); } else { // Use / instead of window since scroll bars affect size. var html = document.documentElement; var body = document.body; rootRect = { x: 0, y: 0, top: 0, left: 0, right: html.clientWidth || body.clientWidth, width: html.clientWidth || body.clientWidth, bottom: html.clientHeight || body.clientHeight, height: html.clientHeight || body.clientHeight }; } return this._expandRectByRootMargin(rootRect); }; /** * Accepts a rect and expands it by the rootMargin value. * @param {Object} rect The rect object to expand. * @return {Object} The expanded rect. * @private */ IntersectionObserver.prototype._expandRectByRootMargin = function(rect) { var margins = this._rootMarginValues.map(function(margin, i) { return margin.unit == 'px' ? margin.value : margin.value * (i % 2 ? rect.width : rect.height) / 100; }); var newRect = { top: rect.top - margins[0], right: rect.right + margins[1], bottom: rect.bottom + margins[2], left: rect.left - margins[3] }; newRect.width = newRect.right - newRect.left; newRect.height = newRect.bottom - newRect.top; newRect.x = newRect.left; newRect.y = newRect.top; return newRect; }; /** * Accepts an old and new entry and returns true if at least one of the * threshold values has been crossed. * @param {?IntersectionObserverEntry} oldEntry The previous entry for a * particular target element or null if no previous entry exists. * @param {IntersectionObserverEntry} newEntry The current entry for a * particular target element. * @return {boolean} Returns true if a any threshold has been crossed. * @private */ IntersectionObserver.prototype._hasCrossedThreshold = function(oldEntry, newEntry) { // To make comparing easier, an entry that has a ratio of 0 // but does not actually intersect is given a value of -1 var oldRatio = oldEntry && oldEntry.isIntersecting ? oldEntry.intersectionRatio || 0 : -1; var newRatio = newEntry.isIntersecting ? newEntry.intersectionRatio || 0 : -1; // Ignore unchanged ratios if (oldRatio === newRatio) return; for (var i = 0; i < this.thresholds.length; i++) { var threshold = this.thresholds[i]; // Return true if an entry matches a threshold or if the new ratio // and the old ratio are on the opposite sides of a threshold. if (threshold == oldRatio || threshold == newRatio || threshold < oldRatio !== threshold < newRatio) { return true; } } }; /** * Returns whether or not the root element is an element and is in the DOM. * @return {boolean} True if the root element is an element and is in the DOM. * @private */ IntersectionObserver.prototype._rootIsInDom = function() { return !this.root || containsDeep(document, this.root); }; /** * Returns whether or not the target element is a child of root. * @param {Element} target The target element to check. * @return {boolean} True if the target element is a child of root. * @private */ IntersectionObserver.prototype._rootContainsTarget = function(target) { return containsDeep(this.root || document, target); }; /** * Adds the instance to the global IntersectionObserver registry if it isn't * already present. * @private */ IntersectionObserver.prototype._registerInstance = function() { if (registry.indexOf(this) < 0) { registry.push(this); } }; /** * Removes the instance from the global IntersectionObserver registry. * @private */ IntersectionObserver.prototype._unregisterInstance = function() { var index = registry.indexOf(this); if (index != -1) registry.splice(index, 1); }; /** * Returns the result of the performance.now() method or null in browsers * that don't support the API. * @return {number} The elapsed time since the page was requested. */ function now() { return window.performance && performance.now && performance.now(); } /** * Throttles a function and delays its execution, so it's only called at most * once within a given time period. * @param {Function} fn The function to throttle. * @param {number} timeout The amount of time that must pass before the * function can be called again. * @return {Function} The throttled function. */ function throttle(fn, timeout) { var timer = null; return function () { if (!timer) { timer = setTimeout(function() { fn(); timer = null; }, timeout); } }; } /** * Adds an event handler to a DOM node ensuring cross-browser compatibility. * @param {Node} node The DOM node to add the event handler to. * @param {string} event The event name. * @param {Function} fn The event handler to add. * @param {boolean} opt_useCapture Optionally adds the even to the capture * phase. Note: this only works in modern browsers. */ function addEvent(node, event, fn, opt_useCapture) { if (typeof node.addEventListener == 'function') { node.addEventListener(event, fn, opt_useCapture || false); } else if (typeof node.attachEvent == 'function') { node.attachEvent('on' + event, fn); } } /** * Removes a previously added event handler from a DOM node. * @param {Node} node The DOM node to remove the event handler from. * @param {string} event The event name. * @param {Function} fn The event handler to remove. * @param {boolean} opt_useCapture If the event handler was added with this * flag set to true, it should be set to true here in order to remove it. */ function removeEvent(node, event, fn, opt_useCapture) { if (typeof node.removeEventListener == 'function') { node.removeEventListener(event, fn, opt_useCapture || false); } else if (typeof node.detatchEvent == 'function') { node.detatchEvent('on' + event, fn); } } /** * Returns the intersection between two rect objects. * @param {Object} rect1 The first rect. * @param {Object} rect2 The second rect. * @return {?Object} The intersection rect or undefined if no intersection * is found. */ function computeRectIntersection(rect1, rect2) { var top = Math.max(rect1.top, rect2.top); var bottom = Math.min(rect1.bottom, rect2.bottom); var left = Math.max(rect1.left, rect2.left); var right = Math.min(rect1.right, rect2.right); var width = right - left; var height = bottom - top; return (width >= 0 && height >= 0) && { x: left, y: top, top: top, bottom: bottom, left: left, right: right, width: width, height: height }; } /** * Shims the native getBoundingClientRect for compatibility with older IE. * @param {Element} el The element whose bounding rect to get. * @return {Object} The (possibly shimmed) rect of the element. */ function getBoundingClientRect(el) { var rect; try { rect = el.getBoundingClientRect(); } catch (err) { // Ignore Windows 7 IE11 "Unspecified error" // https://github.com/w3c/IntersectionObserver/pull/205 } if (!rect) return getEmptyRect(); // Older IE if (!(rect.width && rect.height && rect.x && rect.y)) { rect = { x: rect.left, y: rect.top, top: rect.top, right: rect.right, bottom: rect.bottom, left: rect.left, width: rect.right - rect.left, height: rect.bottom - rect.top }; } return rect; } /** * Returns an empty rect object. An empty rect is returned when an element * is not in the DOM. * @return {Object} The empty rect. */ function getEmptyRect() { return { x: 0, y: 0, top: 0, bottom: 0, left: 0, right: 0, width: 0, height: 0 }; } /** * Checks to see if a parent element contains a child element (including inside * shadow DOM). * @param {Node} parent The parent element. * @param {Node} child The child element. * @return {boolean} True if the parent node contains the child node. */ function containsDeep(parent, child) { var node = child; while (node) { if (node == parent) return true; node = getParentNode(node); } return false; } /** * Gets the parent node of an element or its host element if the parent node * is a shadow root. * @param {Node} node The node whose parent to get. * @return {Node|null} The parent node or null if no parent exists. */ function getParentNode(node) { var parent = node.parentNode; if (parent && parent.nodeType == 11 && parent.host) { // If the parent is a shadow root, return the host element. return parent.host; } if (parent && parent.assignedSlot) { // If the parent is distributed in aStarts at $8.99. Cancel anytime.
Get our most affordable, ad-supported plan.
Watch on Smart TVs, Playstation, Xbox, Chromecast, Apple TV, Blu-ray players, and more.
Save your favorites easily and always have something to watch.
Stream unlimited movies and TV shows on your phone, tablet, laptop, and TV.
Send kids on adventures with their favorite characters in a space made just for them — free with your membership.