387 lines
11 KiB
JavaScript
387 lines
11 KiB
JavaScript
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/**
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* Attaches the scroll event handler
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*
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* @return {void}
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*/
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function attach() {
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var container = this.options.container;
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if (container instanceof HTMLElement) {
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var style = window.getComputedStyle(container);
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if (style.position === 'static') {
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container.style.position = 'relative';
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}
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}
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container.addEventListener('scroll', this._scroll);
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window.addEventListener('resize', this._scroll);
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this._scroll();
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this.attached = true;
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}
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/**
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* Checks an element's position in respect to the viewport
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* and determines wether it's inside the viewport.
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*
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* @param {node} element The DOM node you want to check
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* @return {boolean} A boolean value that indicates wether is on or off the viewport.
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*/
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function inViewport(el) {
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var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : { tolerance: 0 };
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if (!el) {
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throw new Error('You should specify the element you want to test');
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}
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if (typeof el === 'string') {
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el = document.querySelector(el);
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}
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var elRect = el.getBoundingClientRect();
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return (
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// Check bottom boundary
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elRect.bottom - options.tolerance > 0 &&
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// Check right boundary
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elRect.right - options.tolerance > 0 &&
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// Check left boundary
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elRect.left + options.tolerance < (window.innerWidth || document.documentElement.clientWidth) &&
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// Check top boundary
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elRect.top + options.tolerance < (window.innerHeight || document.documentElement.clientHeight)
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);
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}
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/**
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* Checks an element's position in respect to a HTMLElement
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* and determines wether it's within its boundaries.
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*
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* @param {node} element The DOM node you want to check
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* @return {boolean} A boolean value that indicates wether is on or off the container.
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*/
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function inContainer(el) {
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var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : { tolerance: 0, container: '' };
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if (!el) {
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throw new Error('You should specify the element you want to test');
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}
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if (typeof el === 'string') {
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el = document.querySelector(el);
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}
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if (typeof options === 'string') {
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options = {
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tolerance: 0,
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container: document.querySelector(options)
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};
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}
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if (typeof options.container === 'string') {
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options.container = document.querySelector(options.container);
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}
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if (options instanceof HTMLElement) {
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options = {
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tolerance: 0,
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container: options
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};
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}
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if (!options.container) {
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throw new Error('You should specify a container element');
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}
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var containerRect = options.container.getBoundingClientRect();
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return (
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// // Check bottom boundary
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el.offsetTop + el.clientHeight - options.tolerance > options.container.scrollTop &&
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// Check right boundary
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el.offsetLeft + el.clientWidth - options.tolerance > options.container.scrollLeft &&
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// Check left boundary
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el.offsetLeft + options.tolerance < containerRect.width + options.container.scrollLeft &&
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// // Check top boundary
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el.offsetTop + options.tolerance < containerRect.height + options.container.scrollTop
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);
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}
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// TODO: Refactor this so it can be easily tested
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/* istanbul ignore next */
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function eventHandler() {
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var trackedElements = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : {};
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var options = arguments.length > 1 && arguments[1] !== undefined ? arguments[1] : { tolerance: 0 };
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var selectors = Object.keys(trackedElements);
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var testVisibility = void 0;
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if (!selectors.length) return;
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if (options.container === window) {
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testVisibility = inViewport;
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} else {
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testVisibility = inContainer;
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}
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selectors.forEach(function (selector) {
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trackedElements[selector].nodes.forEach(function (item) {
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if (testVisibility(item.node, options)) {
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item.wasVisible = item.isVisible;
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item.isVisible = true;
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} else {
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item.wasVisible = item.isVisible;
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item.isVisible = false;
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}
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if (item.isVisible === true && item.wasVisible === false) {
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if (!trackedElements[selector].enter) return;
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Object.keys(trackedElements[selector].enter).forEach(function (callback) {
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if (typeof trackedElements[selector].enter[callback] === 'function') {
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trackedElements[selector].enter[callback](item.node, 'enter');
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}
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});
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}
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if (item.isVisible === false && item.wasVisible === true) {
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if (!trackedElements[selector].leave) return;
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Object.keys(trackedElements[selector].leave).forEach(function (callback) {
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if (typeof trackedElements[selector].leave[callback] === 'function') {
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trackedElements[selector].leave[callback](item.node, 'leave');
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}
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});
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}
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});
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});
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}
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/**
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* Debounces the scroll event to avoid performance issues
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*
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* @return {void}
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*/
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function debouncedScroll() {
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var _this = this;
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var timeout = void 0;
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return function () {
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clearTimeout(timeout);
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timeout = setTimeout(function () {
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eventHandler(_this.trackedElements, _this.options);
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}, _this.options.debounce);
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};
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}
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/**
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* Removes the scroll event handler
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*
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* @return {void}
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*/
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function destroy() {
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this.options.container.removeEventListener('scroll', this._scroll);
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window.removeEventListener('resize', this._scroll);
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this.attached = false;
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}
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/**
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* Stops tracking elements matching a CSS selector. If a selector has no
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* callbacks it gets removed.
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*
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* @param {string} event The event you want to stop tracking (enter or leave)
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* @param {string} selector The CSS selector you want to stop tracking
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* @return {void}
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*/
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function off(event, selector, handler) {
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var enterCallbacks = Object.keys(this.trackedElements[selector].enter || {});
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var leaveCallbacks = Object.keys(this.trackedElements[selector].leave || {});
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if ({}.hasOwnProperty.call(this.trackedElements, selector)) {
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if (handler) {
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if (this.trackedElements[selector][event]) {
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var callbackName = typeof handler === 'function' ? handler.name : handler;
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delete this.trackedElements[selector][event][callbackName];
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}
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} else {
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delete this.trackedElements[selector][event];
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}
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}
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if (!enterCallbacks.length && !leaveCallbacks.length) {
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delete this.trackedElements[selector];
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}
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}
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/**
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* Starts tracking elements matching a CSS selector
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*
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* @param {string} event The event you want to track (enter or leave)
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* @param {string} selector The element you want to track
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* @param {function} callback The callback function to handle the event
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* @return {void}
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*/
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function on(event, selector, callback) {
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var allowed = ['enter', 'leave'];
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if (!event) throw new Error('No event given. Choose either enter or leave');
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if (!selector) throw new Error('No selector to track');
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if (allowed.indexOf(event) < 0) throw new Error(event + ' event is not supported');
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if (!{}.hasOwnProperty.call(this.trackedElements, selector)) {
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this.trackedElements[selector] = {};
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}
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this.trackedElements[selector].nodes = [];
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for (var i = 0, elems = document.querySelectorAll(selector); i < elems.length; i++) {
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var item = {
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isVisible: false,
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wasVisible: false,
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node: elems[i]
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};
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this.trackedElements[selector].nodes.push(item);
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}
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if (typeof callback === 'function') {
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if (!this.trackedElements[selector][event]) {
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this.trackedElements[selector][event] = {};
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}
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this.trackedElements[selector][event][callback.name || 'anonymous'] = callback;
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}
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}
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/**
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* Observes DOM mutations and runs a callback function when
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* detecting one.
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*
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* @param {node} obj The DOM node you want to observe
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* @param {function} callback The callback function you want to call
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* @return {void}
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*/
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function observeDOM(obj, callback) {
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var MutationObserver = window.MutationObserver || window.WebKitMutationObserver;
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/* istanbul ignore else */
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if (MutationObserver) {
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var obs = new MutationObserver(callback);
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obs.observe(obj, {
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childList: true,
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subtree: true
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});
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} else {
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obj.addEventListener('DOMNodeInserted', callback, false);
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obj.addEventListener('DOMNodeRemoved', callback, false);
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}
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}
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/**
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* Detects wether DOM nodes enter or leave the viewport
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*
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* @constructor
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* @param {object} options The configuration object
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*/
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function OnScreen() {
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var _this = this;
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var options = arguments.length > 0 && arguments[0] !== undefined ? arguments[0] : { tolerance: 0, debounce: 100, container: window };
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this.options = {};
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this.trackedElements = {};
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Object.defineProperties(this.options, {
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container: {
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configurable: false,
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enumerable: false,
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get: function get() {
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var container = void 0;
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if (typeof options.container === 'string') {
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container = document.querySelector(options.container);
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} else if (options.container instanceof HTMLElement) {
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container = options.container;
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}
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return container || window;
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},
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set: function set(value) {
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options.container = value;
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}
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},
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debounce: {
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get: function get() {
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return parseInt(options.debounce, 10) || 100;
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},
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set: function set(value) {
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options.debounce = value;
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}
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},
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tolerance: {
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get: function get() {
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return parseInt(options.tolerance, 10) || 0;
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},
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set: function set(value) {
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options.tolerance = value;
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}
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}
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});
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Object.defineProperty(this, '_scroll', {
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enumerable: false,
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configurable: false,
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writable: false,
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value: this._debouncedScroll.call(this)
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});
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observeDOM(document.querySelector('body'), function () {
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Object.keys(_this.trackedElements).forEach(function (element) {
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_this.on('enter', element);
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_this.on('leave', element);
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});
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});
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this.attach();
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}
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Object.defineProperties(OnScreen.prototype, {
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_debouncedScroll: {
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configurable: false,
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writable: false,
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enumerable: false,
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value: debouncedScroll
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},
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attach: {
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configurable: false,
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writable: false,
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enumerable: false,
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value: attach
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},
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destroy: {
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configurable: false,
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writable: false,
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enumerable: false,
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value: destroy
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},
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off: {
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configurable: false,
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writable: false,
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enumerable: false,
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value: off
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},
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on: {
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configurable: false,
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writable: false,
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enumerable: false,
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value: on
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}
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});
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OnScreen.check = inViewport;
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export default OnScreen;
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//# sourceMappingURL=on-screen.es6.js.map
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