Net/docs/api/scripts/platform-content-handler.js

filteringContext = {
    dependencies: {},
    restrictedDependencies: [],
    activeFilters: []
}
let highlightedAnchor;
let topNavbarOffset;

window.addEventListener('load', () => {
    document.querySelectorAll("div[data-platform-hinted]")
        .forEach(elem => elem.addEventListener('click', (event) => togglePlatformDependent(event,elem)))
    document.querySelectorAll("div[tabs-section]")
        .forEach(elem => elem.addEventListener('click', (event) => toggleSectionsEventHandler(event)))
    const filterSection = document.getElementById('filter-section')
    if (filterSection) {
        filterSection.addEventListener('click', (event) => filterButtonHandler(event))
        initializeFiltering()
    }
    initTabs()
    handleAnchor()
    initHidingLeftNavigation()

    document.getElementById('main').addEventListener("scroll", (e) => {
        document.getElementsByClassName("navigation-wrapper")[0].classList.toggle("sticky-navigation", e.target.scrollTop > 0)
    })
    topNavbarOffset = document.getElementById('navigation-wrapper')
})

const initHidingLeftNavigation = () => {
    document.getElementById("leftToggler").onclick = function(event) {
        //Events need to be prevented from bubbling since they will trigger next handler
        event.preventDefault();
        event.stopPropagation();
        event.stopImmediatePropagation();
        document.getElementById("leftColumn").classList.toggle("open");
    }

    document.getElementById("main").onclick = () => {
        document.getElementById("leftColumn").classList.remove("open");
    }
}

// Hash change is needed in order to allow for linking inside the same page with anchors
// If this is not present user is forced to refresh the site in order to use an anchor
window.onhashchange = handleAnchor

function scrollToElementInContent(element){
    const scrollToElement = () => document.getElementById('main').scrollTo({ top: element.offsetTop - topNavbarOffset.offsetHeight, behavior: "smooth"})

    const waitAndScroll = () => {
        setTimeout(() => {
            if(topNavbarOffset){
                scrollToElement()
            } else {
                waitForScroll()
            }
        }, 50)
    }

    if(topNavbarOffset){
        scrollToElement()
    } else {
        waitAndScroll()
    }
}


function handleAnchor() {
    if(highlightedAnchor){
        highlightedAnchor.classList.remove('anchor-highlight')
        highlightedAnchor = null;
    }

    let searchForTab = function(element) {
        if(element && element.hasAttribute) {
            if(element.hasAttribute("data-togglable")) return element;
            else return searchForTab(element.parentNode)
        } else return null
    }
    let anchor = window.location.hash
    if (anchor != "") {
        anchor = anchor.substring(1)
        let element = document.querySelector('a[data-name="' + anchor+'"]')
        if (element) {
            let tab = searchForTab(element)
            if (tab) {
                toggleSections(tab)
            }
            const content = element.nextElementSibling
            if(content){
                content.classList.add('anchor-highlight')
                highlightedAnchor = content
            }

            scrollToElementInContent(element)
        }
    }
}

function initTabs(){
    document.querySelectorAll("div[tabs-section]")
        .forEach(element => {
            showCorrespondingTabBody(element)
            element.addEventListener('click', (event) => toggleSectionsEventHandler(event))
        })
    let cached = localStorage.getItem("active-tab")
    if (cached) {
        let parsed = JSON.parse(cached)
        let tab = document.querySelector('div[tabs-section] > button[data-togglable="' + parsed + '"]')
        if(tab) {
            toggleSections(tab)
        }
    }
}

function showCorrespondingTabBody(element){
    const key = element.querySelector("button[data-active]").getAttribute("data-togglable")
    document.querySelector(".tabs-section-body")
        .querySelector("div[data-togglable='" + key + "']")
        .setAttribute("data-active", "")
}

function filterButtonHandler(event) {
        if(event.target.tagName == "BUTTON" && event.target.hasAttribute("data-filter")) {
            let sourceset = event.target.getAttribute("data-filter")
            if(filteringContext.activeFilters.indexOf(sourceset) != -1) {
                filterSourceset(sourceset)
            } else {
                unfilterSourceset(sourceset)
            }
        }
}

function initializeFiltering() {
    filteringContext.dependencies = JSON.parse(sourceset_dependencies)
    document.querySelectorAll("#filter-section > button")
        .forEach(p => filteringContext.restrictedDependencies.push(p.getAttribute("data-filter")))
    Object.keys(filteringContext.dependencies).forEach(p => {
        filteringContext.dependencies[p] = filteringContext.dependencies[p]
            .filter(q => -1 !== filteringContext.restrictedDependencies.indexOf(q))
    })
    let cached = window.localStorage.getItem('inactive-filters')
    if (cached) {
        let parsed = JSON.parse(cached)
        //Events are used by react to get values in 'on this page'
        const event = new CustomEvent('sourceset-filter-change', { detail: parsed });
        window.dispatchEvent(event);

        filteringContext.activeFilters = filteringContext.restrictedDependencies
            .filter(q => parsed.indexOf(q) == -1 )
    } else {
        filteringContext.activeFilters = filteringContext.restrictedDependencies
    }
    refreshFiltering()
}

function filterSourceset(sourceset) {
    filteringContext.activeFilters = filteringContext.activeFilters.filter(p => p != sourceset)
    refreshFiltering()
    addSourcesetFilterToCache(sourceset)
}

function unfilterSourceset(sourceset) {
    if(filteringContext.activeFilters.length == 0) {
        filteringContext.activeFilters = filteringContext.dependencies[sourceset].concat([sourceset])
        refreshFiltering()
        filteringContext.dependencies[sourceset].concat([sourceset]).forEach(p => removeSourcesetFilterFromCache(p))
    } else {
        filteringContext.activeFilters.push(sourceset)
        refreshFiltering()
        removeSourcesetFilterFromCache(sourceset)
    }

}

function addSourcesetFilterToCache(sourceset) {
    let cached = localStorage.getItem('inactive-filters')
    if (cached) {
        let parsed = JSON.parse(cached)
        localStorage.setItem('inactive-filters', JSON.stringify(parsed.concat([sourceset])))
    } else {
        localStorage.setItem('inactive-filters', JSON.stringify([sourceset]))
    }
}

function removeSourcesetFilterFromCache(sourceset) {
    let cached = localStorage.getItem('inactive-filters')
    if (cached) {
        let parsed = JSON.parse(cached)
        localStorage.setItem('inactive-filters', JSON.stringify(parsed.filter(p => p != sourceset)))
    }
}

function toggleSections(target) {
    localStorage.setItem('active-tab', JSON.stringify(target.getAttribute("data-togglable")))
    const activateTabs = (containerClass) => {
        for(const element of document.getElementsByClassName(containerClass)){
            for(const child of element.children){
                if(child.getAttribute("data-togglable") === target.getAttribute("data-togglable")){
                    child.setAttribute("data-active", "")
                } else {
                    child.removeAttribute("data-active")
                }
            }
        }
    }

    activateTabs("tabs-section")
    activateTabs("tabs-section-body")
}

function toggleSectionsEventHandler(evt){
    if(!evt.target.getAttribute("data-togglable")) return
    toggleSections(evt.target)
}

function togglePlatformDependent(e, container) {
    let target = e.target
    if (target.tagName != 'BUTTON') return;
    let index = target.getAttribute('data-toggle')

    for(let child of container.children){
        if(child.hasAttribute('data-toggle-list')){
            for(let bm of child.children){
                if(bm == target){
                    bm.setAttribute('data-active',"")
                } else if(bm != target) {
                    bm.removeAttribute('data-active')
                }
            }
        }
        else if(child.getAttribute('data-togglable') == index) {
           child.setAttribute('data-active',"")
        }
        else {
            child.removeAttribute('data-active')
        }
    }
}

function refreshFiltering() {
    let sourcesetList = filteringContext.activeFilters
    document.querySelectorAll("[data-filterable-set]")
        .forEach(
            elem => {
                let platformList = elem.getAttribute("data-filterable-set").split(' ').filter(v => -1 !== sourcesetList.indexOf(v))
                elem.setAttribute("data-filterable-current", platformList.join(' '))
            }
        )
    const event = new CustomEvent('sourceset-filter-change', { detail: sourcesetList });
    window.dispatchEvent(event);
    
    refreshFilterButtons()
    refreshPlatformTabs()
}

function refreshPlatformTabs() {
    document.querySelectorAll(".platform-hinted > .platform-bookmarks-row").forEach(
        p => {
            let active = false;
            let firstAvailable = null
            p.childNodes.forEach(
                element => {
                    if(element.getAttribute("data-filterable-current") != ''){
                        if( firstAvailable == null) {
                            firstAvailable = element
                        }
                        if(element.hasAttribute("data-active")) {
                            active = true;
                        }
                    }
                }
            )
            if( active == false && firstAvailable) {
                firstAvailable.click()
            }
        }
    )
}

function refreshFilterButtons() {
    document.querySelectorAll("#filter-section > button")
        .forEach(f => {
            if(filteringContext.activeFilters.indexOf(f.getAttribute("data-filter")) != -1){
                f.setAttribute("data-active","")
            } else {
                f.removeAttribute("data-active")
            }
        })
}