Create tickers and events utils

assets/scripts/utils/events.js

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+import { debounce } from './tickers'
+
+CUSTOM_EVENT_LISTENERS = []
+
+/**
+ * Check if element is Window
+ * @param  {DOMElement} $el - Element to check
+ * @return {boolean}    True if window
+ */
+
+const isWindow = $el => $el === window
+
+
+/**
+ * Check if element is a DOM element
+ * @param  {DOMElement} $el - Element to check
+ * @return {boolean}    True if dom element
+ */
+
+const isDomElement = $el => ($el instanceof Element || $el instanceof HTMLDocument || $el instanceof HTMLDocument)
+
+
+/**
+ * Check if element is Window or DOM element
+ * @param  {Element}    $el - Element to check
+ * @return {boolean}    True if window or DOM element
+ */
+
+const isValidElement = $el => (isWindow($el) || isDomElement($el))
+
+
+/**
+ * Check if element already has the event attached
+ * @param  {Element}    $el     - Element where the event is attached
+ * @param  {String}     event   - The event name
+ * @return {Boolean}    True if the event is already attached to the element
+ */
+
+const customEventIsDefined = ($el, event) => CUSTOM_EVENT_LISTENERS.findIndex(e => e.$el === $el && e.event === event) > -1
+
+
+/**
+ * Add custom event to event storage
+ * @param  {Element}    $el     - Element where the event is attached
+ * @param  {String}     event   - The event name
+ * @return {void}
+ */
+
+const addCustomEvent = ($el, event) => {
+    if(!customEventIsDefined($el, event)) {
+        CUSTOM_EVENT_LISTENERS.push({
+            $el,
+            event
+        })
+    }
+}
+
+
+/**
+ * Create a sarting event for the event triggered
+ * @param  {Element}    EventTarget     - Element to bind the event to
+ * @param  {object}     event   - The triggered event's name
+ * @return {void}
+ */
+
+const addStartEvent = (EventTarget, event, delay = 200) => {
+
+    const eventName = `${event}Start`
+
+    // Check element
+    if(!isValidElement(EventTarget)) {
+        console.warn(`[addStartEvent:${eventName}]: Wrong parameter '${el}'. The parameter must be document, window or a DOM element`)
+        return
+    }
+
+    // Check if event already exists
+    if(customEventIsDefined(EventTarget, eventName)) {
+        console.log(`[addStartEvent:${eventName}]: Already exists for '${el}' element`)
+        return
+    }
+
+    // Register element and event
+    addCustomEvent(EventTarget, eventName)
+
+    // Create event
+    const startEvent = new CustomEvent(eventName)
+    EventTarget.addEventListener(event, debounce(() => {
+        EventTarget.dispatchEvent(startEvent)
+    }, delay, true))
+}
+
+/**
+ * Create an ending event for the event triggered
+ * @param  {Element}    EventTarget     - Element to bind the event to
+ * @param  {object}     event   - The triggered event's name
+ * @return {void}
+ */
+
+const addEndEvent = (EventTarget, event, delay = 200) => {
+
+    const eventName = `${event}End`
+
+    // Check element
+    if(!isValidElement(EventTarget)) {
+        console.warn(`[addEndEvent:${eventName}]: Wrong parameter '${el}'. The parameter must be document, window or a DOM element`)
+        return
+    }
+
+    // Check if event already exists
+    if(customEventIsDefined(EventTarget, eventName)) {
+        console.log(`[addEndEvent:${eventName}]: Already exists for '${el}' element`)
+        return
+    }
+
+    // Register element and event
+    addCustomEvent(EventTarget, eventName)
+
+    // Create event
+    const endEvent = new CustomEvent(eventName)
+    EventTarget.addEventListener(event, debounce(() => {
+        EventTarget.dispatchEvent(endEvent)
+    }, delay))
+}
+
+
+/**
+ * Add scrollUp event to element (window by default)
+ * @param  {Element} EventTarget - Element to bind the event to
+ * @return {void}
+ */
+
+const addScrollUpEvent = (EventTarget = window) => {
+
+    // Check element
+    if(!isValidElement(EventTarget)) {
+        console.warn(`[addScrollUpEvent]: Wrong parameter '${el}'. The parameter must be window or a DOM element`)
+        return
+    }
+
+    let scrollTop = EventTarget.scrollTop
+    let previousScrollTop = scrollTop
+    let direction = 0
+    const scrollUp = new CustomEvent('scrollUp')
+    const scrollProperty = isWindow(EventTarget) ? 'scrollY' : 'scrollTop'
+
+    EventTarget.addEventListener('scroll', e => {
+        scrollTop = EventTarget[scrollProperty]
+
+        // Scroll up
+        if(scrollTop < previousScrollTop && direction > -1) {
+            EventTarget.dispatchEvent(scrollUp)
+            direction = -1
+
+        // Scroll down
+        } else if(scrollTop > previousScrollTop && direction < 1) {
+            direction = 1
+        }
+
+        previousScrollTop = scrollTop
+    })
+}
+
+
+/**
+ * Add scrollDown event to element (window by default)
+ * @param  {Element} EventTarget - Element to bind the event to
+ * @return {void}
+ */
+
+const addScrollDownEvent = (EventTarget = window) => {
+
+    // Check element
+    if(!isValidElement(EventTarget)) {
+        console.warn(`[addScrollDownEvent]: Wrong parameter '${el}'. The parameter must be window or a DOM element`)
+        return
+    }
+
+    let scrollTop = EventTarget.scrollTop
+    let previousScrollTop = scrollTop
+    let direction = 0
+    const scrollDown = new CustomEvent('scrollDown')
+    const scrollProperty = isWindow(EventTarget) ? 'scrollY' : 'scrollTop'
+
+    EventTarget.addEventListener('scroll', e => {
+        scrollTop = EventTarget[scrollProperty]
+
+        // Scroll up
+        if(scrollTop < previousScrollTop && direction > -1) {
+            direction = -1
+
+        // Scroll down
+        } else if(scrollTop > previousScrollTop && direction < 1) {
+            EventTarget.dispatchEvent(scrollDown)
+            direction = 1
+        }
+
+        previousScrollTop = scrollTop
+    })
+}
+
+export {
+    addStartEvent,
+    addEndEvent,
+    addScrollUpEvent,
+    addScrollDownEvent,
+}

assets/scripts/utils/tickers.js

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+/**
+ * Debounce function: fire the callback before/after the action has finished for the defined amount of time
+ * @param {function}    callback    - callback function
+ * @param {number}      delay       - waiting time in milisecond
+ * @param {boolean}     immediate   - triggers before or after delay
+ * @return {function}   callback
+ */
+
+const debounce = (callback, delay, immediate = false) => {
+    let timeout = null
+
+    return (...args) => {
+        clearTimeout(timeout)
+
+        const later = () => {
+            timeout = null
+            if (!immediate) {
+                callback(...args)
+            }
+        }
+
+        if (immediate && !timeout) {
+            callback(...args)
+        }
+
+        timeout = setTimeout(later, delay)
+    }
+}
+
+
+/**
+ * Throttle function: fire the callback while the action is being performed for the defined iteration time
+ * @param {function}    callback    - callback function
+ * @param {number}      delay       - waiting time in milisecond
+ * @return {function}   callback
+ */
+
+const throttle = (callback, delay) => {
+    let timeout = false
+
+    return (...args) => {
+        if (!timeout) {
+            timeout = true
+
+            callback(...args)
+
+            setTimeout(() => {
+                timeout = false
+            }, delay)
+        }
+    }
+}
+
+
+export {
+    debounce,
+    throttle
+}