position-indicator/dist/index.cjs

position indicator library

/*!
 * position-indicator v0.0.12
 * (c) kunukn
 * Released under the MIT License.
 */

'use strict';

Object.defineProperty(exports, '__esModule', { value: true });

var _getFullDocumentHeight = function () {
    return Math.max(document.body.scrollHeight, document.documentElement.scrollHeight);
};
var _getViewPortHeight = function () { return window.innerHeight; };
var _getScrollYPosition = function () { return window.pageYOffset; };
var _hasScroll = function () { return _getFullDocumentHeight() > _getViewPortHeight(); };
var _clamp = function (value, min, max) {
    return Math.min(Math.max(value, min), max);
};
var _onUpdate = function (eventType, memory) {
    var fullDocumentHeight = _getFullDocumentHeight();
    var viewPortHeight = _getViewPortHeight();
    var scrollYPosition = _getScrollYPosition();
    var relative = fullDocumentHeight - viewPortHeight;
    var position = _clamp(scrollYPosition / (relative || 1), 0, 1);
    var prevPosition = memory.prevPosition;
    memory.prevPosition = position;
    return {
        position: position,
        prevPosition: prevPosition,
        hasUpdated: position !== prevPosition,
        eventType: eventType,
        hasScroll: _hasScroll(),
        eventDate: Date.now(),
    };
};
var _init = function (_a, events, memory) {
    var initCallback = _a.onInit, updateCallback = _a.onUpdate, _b = _a.useResizeListener, useResizeListener = _b === void 0 ? true : _b, _c = _a.useResizeObserver, useResizeObserver = _c === void 0 ? true : _c;
    events.onScroll = function () {
        if (updateCallback) {
            updateCallback(_onUpdate('scroll', memory));
        }
    };
    if (useResizeListener) {
        events.onResize = function () {
            if (updateCallback) {
                updateCallback(_onUpdate('resize', memory));
            }
        };
    }
    if (useResizeObserver) {
        events.onHeightChange = function () {
            if (updateCallback) {
                updateCallback(_onUpdate('heightChange', memory));
            }
        };
        if (typeof ResizeObserver !== 'undefined') {
            events.resizeObserver = new ResizeObserver(events.onHeightChange);
            events.resizeObserver.observe(document.body);
        }
    }
    /**
     * Throttling for event is not used.
     * Because it has the same effect same as rAF.
     * https://stackoverflow.com/a/44779316/815507
     */
    window.addEventListener('scroll', events.onScroll);
    window.addEventListener('resize', events.onResize);
    initCallback && initCallback(_onUpdate('init', memory));
};
var _destroy = function (events) {
    events.onScroll && window.removeEventListener('scroll', events.onScroll);
    events.onResize && window.removeEventListener('resize', events.onResize);
    events.resizeObserver && events.resizeObserver.unobserve(document.body);
};
var createPositionIndicator = function (options) {
    var events = {
        onScroll: null,
        onResize: null,
        onHeightChange: null,
        resizeObserver: null,
    };
    var memory = {};
    return {
        init: function () { return _init(options, events, memory); },
        destroy: function () {
            _destroy(events);
            events = {};
            memory = {};
        },
    };
};

exports.createPositionIndicator = createPositionIndicator;
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