isekai_wiki_app/assets/js/app_bridge.js

var _InAppWebViewReady = false;

var enableScrollSpy = true;
var titleList = [];
var currentTitle = '_top';
var titleOffset = 10;

window.MugenApp = {
    emit: function() {
        window.flutter_inappwebview.callHandler.apply(this, arguments);
    },
    scrollToTitle: function (anchor) {
        var el = document.getElementById(anchor);
        if (el) {
            var scrollTop = window.scrollY + el.getBoundingClientRect().top;
            if (navigator.safeArea) {
                scrollTop -= navigator.safeArea.top + titleOffset;
            }
            scrollTop = Math.max(0, scrollTop);
            
            enableScrollSpy = false;
            window.scrollTo({
                top: scrollTop,
            });

            setTimeout(function() {
                enableScrollSpy = true;
            }, 50);
        }
    },
};

function onReadyStateChange() {
    if (_InAppWebViewReady && document.readyState === "complete") {
        titleList = document.querySelectorAll('.mw-parser-output h1, .mw-parser-output h2, .mw-parser-output h3, .mw-parser-output h4, .mw-parser-output h5, .mw-parser-output h6');
        window.MugenApp.emit('pageLoaded', true);
    }
}
window.addEventListener("flutterInAppWebViewPlatformReady", function(event) {
    _InAppWebViewReady = true;
    window.MugenApp.emit('bridgeConnected', true);
    onReadyStateChange();
});

document.addEventListener("readystatechange", onReadyStateChange);

var _debouceTimer = null;
function debouce(callback, ms) {
    return function() {
        var _args = arguments;
        if (!_debouceTimer) {
            _debouceTimer = setTimeout(function() {
                callback.apply(this, _args);
                _debouceTimer = null;
            }, ms);
        }
    }
}

document.addEventListener('scroll', debouce(function() {
    if (!enableScrollSpy || !titleList || titleList.length === 0) return true;

    var offsetTop = (navigator.safeArea ? navigator.safeArea.top : 0) + titleOffset; 

    var currentTitleEl = null;
    var isFirstSection = false;
    for (var i = 0; i < titleList.length; i ++) {
        var el = titleList[i];
        var pos = el.getBoundingClientRect();
        if (pos.top - offsetTop > 0) {
            if (i === 0) {
                isFirstSection = true;
            } else {
                currentTitleEl = titleList[i - 1];
            }
            break;
        }
    }
    if (!currentTitleEl && !isFirstSection) {
        currentTitleEl = titleList[titleList.length - 1];
    }
 
    var newCurrentTitle;
    if (isFirstSection) {
        newCurrentTitle = '_firstSection';
    } else {
        var currentTitleAnchorEl = currentTitleEl.querySelector('.mw-headline');
        if (currentTitleAnchorEl) {
            newCurrentTitle = currentTitleAnchorEl.id;
        }
    }

    if (newCurrentTitle && newCurrentTitle !== currentTitle) {
        currentTitle = newCurrentTitle;
        window.MugenApp.emit('sectionChange', newCurrentTitle);
    }
}, 200), { passive: true });