@aws-amplify/analytics/dist/esm/trackers/PageViewTracker.mjs

Analytics category of aws-amplify

import { ConsoleLogger } from '@aws-amplify/core';
import { isBrowser } from '@aws-amplify/core/internals/utils';

// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0
const logger = new ConsoleLogger('PageViewTracker');
const DEFAULT_EVENT_NAME = 'pageView';
const DEFAULT_APP_TYPE = 'singlePage';
const DEFAULT_URL_PROVIDER = () => {
    return window.location.origin + window.location.pathname;
};
const PREV_URL_STORAGE_KEY = 'aws-amplify-analytics-prevUrl';
/**
 * Custom event broadcast by the shared history patch (see below) whenever
 * `history.pushState` / `history.replaceState` is invoked. Every active
 * `PageViewTracker` subscribes to it, so a single global patch can drive any
 * number of concurrent tracker instances.
 */
const SPA_NAVIGATION_EVENT = 'amplify-analytics-spa-navigation';
/**
 * Reference-counted, process-global patch of the History API.
 *
 * `PageViewTracker` instances previously each installed their own revocable
 * proxy on `window.history.pushState` / `replaceState`. That is not safe once
 * more than one instance can exist at a time (e.g. `pageView` auto-track enabled
 * on both Pinpoint and Kinesis): the proxies stacked (each instance captured the
 * previous instance's proxy as its "original"), so only the last-installed
 * instance actually received SPA navigations, and disabling providers in the
 * wrong order could leave a revoked proxy installed — throwing on the next
 * `pushState`.
 *
 * Instead the History API is patched exactly once (guarded by a reference
 * count). The patch simply forwards to the native implementation and broadcasts
 * {@link SPA_NAVIGATION_EVENT}; each tracker instance listens for that event.
 * The patch is removed and the native methods restored only when the last
 * instance tears down, so any number of trackers can be enabled / disabled in
 * any order safely.
 */
let historyPatchRefCount = 0;
let nativePushState;
let nativeReplaceState;
const installHistoryPatch = () => {
    historyPatchRefCount += 1;
    // The patch is shared across all instances; only install it once.
    if (historyPatchRefCount > 1) {
        return;
    }
    nativePushState = window.history.pushState;
    nativeReplaceState = window.history.replaceState;
    const dispatchNavigation = () => {
        window.dispatchEvent(new Event(SPA_NAVIGATION_EVENT));
    };
    window.history.pushState = function pushState(...args) {
        nativePushState.apply(this, args);
        dispatchNavigation();
    };
    window.history.replaceState = function replaceState(...args) {
        nativeReplaceState.apply(this, args);
        dispatchNavigation();
    };
};
const uninstallHistoryPatch = () => {
    if (historyPatchRefCount === 0) {
        return;
    }
    historyPatchRefCount -= 1;
    // Keep the patch installed while other instances still rely on it.
    if (historyPatchRefCount > 0) {
        return;
    }
    if (nativePushState) {
        window.history.pushState = nativePushState;
        nativePushState = undefined;
    }
    if (nativeReplaceState) {
        window.history.replaceState = nativeReplaceState;
        nativeReplaceState = undefined;
    }
};
class PageViewTracker {
    constructor(eventRecorder, options, namespace) {
        this.options = {};
        this.trackerActive = true;
        this.eventRecorder = eventRecorder;
        this.spaTrackingActive = false;
        this.storageKey = namespace
            ? `${PREV_URL_STORAGE_KEY}-${namespace}`
            : PREV_URL_STORAGE_KEY;
        this.handleLocationChange = this.handleLocationChange.bind(this);
        this.configure(eventRecorder, options);
    }
    configure(eventRecorder, options) {
        this.eventRecorder = eventRecorder;
        // Clean up any existing listeners
        this.cleanup();
        // Apply defaults
        this.options = {
            appType: options?.appType ?? DEFAULT_APP_TYPE,
            attributes: options?.attributes ?? undefined,
            eventName: options?.eventName ?? DEFAULT_EVENT_NAME,
            urlProvider: options?.urlProvider ?? DEFAULT_URL_PROVIDER,
        };
        // Configure SPA or MPA page view tracking
        if (isBrowser()) {
            if (this.options.appType === 'singlePage') {
                this.setupSPATracking();
            }
            else {
                this.setupMPATracking();
            }
            this.trackerActive = true;
        }
    }
    cleanup() {
        // No-op if document listener is not active
        if (!this.trackerActive) {
            return;
        }
        // Clean up SPA page view listeners
        if (this.spaTrackingActive) {
            window.removeEventListener(SPA_NAVIGATION_EVENT, this.handleLocationChange);
            window.removeEventListener('popstate', this.handleLocationChange);
            uninstallHistoryPatch();
            this.spaTrackingActive = false;
        }
    }
    setupSPATracking() {
        if (!this.spaTrackingActive) {
            // Subscribe to the shared history patch (installed once, ref-counted)
            // plus native `popstate`. Both funnel through `handleLocationChange`.
            installHistoryPatch();
            window.addEventListener(SPA_NAVIGATION_EVENT, this.handleLocationChange);
            window.addEventListener('popstate', this.handleLocationChange);
            sessionStorage.removeItem(this.storageKey);
            this.spaTrackingActive = true;
        }
    }
    setupMPATracking() {
        this.handleLocationChange();
    }
    handleLocationChange() {
        const currentUrl = this.options.urlProvider();
        const eventName = this.options.eventName || DEFAULT_EVENT_NAME;
        if (this.urlHasChanged()) {
            sessionStorage.setItem(this.storageKey, currentUrl);
            // Assemble attribute list
            const attributes = Object.assign({
                url: currentUrl,
            }, this.options.attributes);
            logger.debug('Recording automatically tracked page view event', {
                eventName,
                attributes,
            });
            this.eventRecorder(eventName, attributes);
        }
    }
    urlHasChanged() {
        const prevUrl = sessionStorage.getItem(this.storageKey);
        const currUrl = this.options.urlProvider();
        return currUrl !== prevUrl;
    }
}

export { PageViewTracker };
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