/
url-change-tracker.js
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/
url-change-tracker.js
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/**
* Copyright 2016 Google Inc. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import MethodChain from '../method-chain';
import provide from '../provide';
import TrackerQueue from '../tracker-queue';
import {plugins, trackUsage} from '../usage';
import {assign, createFieldsObj, now} from '../utilities';
/**
* Class for the `urlChangeTracker` analytics.js plugin.
* @implements {UrlChangeTrackerPublicInterface}
*/
class UrlChangeTracker {
/**
* Adds handler for the history API methods
* @param {!Tracker} tracker Passed internally by analytics.js
* @param {?Object} opts Passed by the require command.
*/
constructor(tracker, opts) {
trackUsage(tracker, plugins.URL_CHANGE_TRACKER);
// Feature detects to prevent errors in unsupporting browsers.
if (!history.pushState || !window.addEventListener) return;
/** @type {UrlChangeTrackerOpts} */
const defaultOpts = {
shouldTrackUrlChange: this.shouldTrackUrlChange,
trackReplaceState: false,
fieldsObj: {},
hitFilter: null,
};
this.opts = /** @type {UrlChangeTrackerOpts} */ (assign(defaultOpts, opts));
this.tracker = tracker;
// Sets the initial page field.
// Don't set this on the tracker yet so campaign data can be retreived
// from the location field.
this.path = getPath();
this.queue = TrackerQueue.getOrCreate(tracker.get('trackingId'));
// Binds methods.
this.pushStateOverride = this.pushStateOverride.bind(this);
this.replaceStateOverride = this.replaceStateOverride.bind(this);
this.handlePopState = this.handlePopState.bind(this);
// Watches for history changes.
MethodChain.add(history, 'pushState', this.pushStateOverride);
MethodChain.add(history, 'replaceState', this.replaceStateOverride);
window.addEventListener('popstate', this.handlePopState);
}
/**
* Handles invocations of the native `history.pushState` and calls
* `handleUrlChange()` indicating that the history updated.
* @param {!Function} originalMethod A reference to the overridden method.
* @return {!Function}
*/
pushStateOverride(originalMethod) {
return (...args) => {
originalMethod(...args);
this.handleUrlChange(true);
};
}
/**
* Handles invocations of the native `history.replaceState` and calls
* `handleUrlChange()` indicating that history was replaced.
* @param {!Function} originalMethod A reference to the overridden method.
* @return {!Function}
*/
replaceStateOverride(originalMethod) {
return (...args) => {
originalMethod(...args);
this.handleUrlChange(false);
};
}
/**
* Handles responding to the popstate event and calls
* `handleUrlChange()` indicating that history was updated.
*/
handlePopState() {
this.handleUrlChange(true);
}
/**
* Updates the page and title fields on the tracker and sends a pageview
* if a new history entry was created.
* @param {boolean} historyDidUpdate True if the history was changed via
* `pushState()` or the `popstate` event. False if the history was just
* modified via `replaceState()`.
*/
handleUrlChange(historyDidUpdate) {
// Call the update logic asychronously to help ensure that app logic
// responding to the URL change happens prior to this.
setTimeout(() => {
const oldPath = this.path;
const newPath = getPath();
if (oldPath != newPath &&
this.opts.shouldTrackUrlChange.call(this, newPath, oldPath)) {
this.path = newPath;
/** @type {FieldsObj} */
const newFields = {
page: newPath,
title: document.title,
};
this.tracker.set(newFields);
if (historyDidUpdate || this.opts.trackReplaceState) {
// Pass the new fields here in addition to setting them above
// on the off-chance that another URL change happens before this
// one gets sent.
this.sendPageview(newFields);
}
}
}, 0);
}
/**
* Sends a pageview hit when idle.
* @param {!FieldsObj} fieldsObj
*/
sendPageview(fieldsObj) {
this.queue.pushTask(({time}) => {
/** @type {FieldsObj} */
const defaultFields = {
transport: 'beacon',
page: fieldsObj.page,
title: fieldsObj.title,
queueTime: now() - time,
};
this.tracker.send('pageview', createFieldsObj(defaultFields,
this.opts.fieldsObj, this.tracker, this.opts.hitFilter));
});
}
/**
* Determines whether or not the tracker should send a hit with the new page
* data. This default implementation can be overrided in the config options.
* @param {string} newPath The path after the URL change.
* @param {string} oldPath The path prior to the URL change.
* @return {boolean} Whether or not the URL change should be tracked.
*/
shouldTrackUrlChange(newPath, oldPath) {
return !!(newPath && oldPath);
}
/**
* Removes all event listeners and restores overridden methods.
*/
remove() {
this.queue.destroy();
MethodChain.remove(history, 'pushState', this.pushStateOverride);
MethodChain.remove(history, 'replaceState', this.replaceStateOverride);
window.removeEventListener('popstate', this.handlePopState);
}
}
provide('urlChangeTracker', UrlChangeTracker);
/**
* @return {string} The path value of the current URL.
*/
function getPath() {
return location.pathname + location.search;
}