// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
if (!_flutter) {
var _flutter = {};
}
_flutter.loader = null;
(function () {
"use strict";
const baseUri = ensureTrailingSlash(getBaseURI());
function getBaseURI() {
const base = document.querySelector("base");
return (base && base.getAttribute("href")) || "";
}
function ensureTrailingSlash(uri) {
if (uri == "") {
return uri;
}
return uri.endsWith("/") ? uri : `${uri}/`;
}
/**
* Wraps `promise` in a timeout of the given `duration` in ms.
*
* Resolves/rejects with whatever the original `promises` does, or rejects
* if `promise` takes longer to complete than `duration`. In that case,
* `debugName` is used to compose a legible error message.
*
* If `duration` is < 0, the original `promise` is returned unchanged.
* @param {Promise} promise
* @param {number} duration
* @param {string} debugName
* @returns {Promise} a wrapped promise.
*/
async function timeout(promise, duration, debugName) {
if (duration < 0) {
return promise;
}
let timeoutId;
const _clock = new Promise((_, reject) => {
timeoutId = setTimeout(() => {
reject(
new Error(
`${debugName} took more than ${duration}ms to resolve. Moving on.`,
{
cause: timeout,
}
)
);
}, duration);
});
return Promise.race([promise, _clock]).finally(() => {
clearTimeout(timeoutId);
});
}
/**
* Handles the creation of a TrustedTypes `policy` that validates URLs based
* on an (optional) incoming array of RegExes.
*/
class FlutterTrustedTypesPolicy {
/**
* Constructs the policy.
* @param {[RegExp]} validPatterns the patterns to test URLs
* @param {String} policyName the policy name (optional)
*/
constructor(validPatterns, policyName = "flutter-js") {
const patterns = validPatterns || [
/\.js$/,
];
if (window.trustedTypes) {
this.policy = trustedTypes.createPolicy(policyName, {
createScriptURL: function(url) {
const parsed = new URL(url, window.location);
const file = parsed.pathname.split("/").pop();
const matches = patterns.some((pattern) => pattern.test(file));
if (matches) {
return parsed.toString();
}
console.error(
"URL rejected by TrustedTypes policy",
policyName, ":", url, "(download prevented)");
}
});
}
}
}
/**
* Handles loading/reloading Flutter's service worker, if configured.
*
* @see: https://developers.google.com/web/fundamentals/primers/service-workers
*/
class FlutterServiceWorkerLoader {
/**
* Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
* @param {TrustedTypesPolicy | undefined} policy
*/
setTrustedTypesPolicy(policy) {
this._ttPolicy = policy;
}
/**
* Returns a Promise that resolves when the latest Flutter service worker,
* configured by `settings` has been loaded and activated.
*
* Otherwise, the promise is rejected with an error message.
* @param {*} settings Service worker settings
* @returns {Promise} that resolves when the latest serviceWorker is ready.
*/
loadServiceWorker(settings) {
if (settings == null) {
// In the future, settings = null -> uninstall service worker?
console.debug("Null serviceWorker configuration. Skipping.");
return Promise.resolve();
}
if (!("serviceWorker" in navigator)) {
let errorMessage = "Service Worker API unavailable.";
if (!window.isSecureContext) {
errorMessage += "\nThe current context is NOT secure."
errorMessage += "\nRead more: https://developer.mozilla.org/en-US/docs/Web/Security/Secure_Contexts";
}
return Promise.reject(
new Error(errorMessage)
);
}
const {
serviceWorkerVersion,
serviceWorkerUrl = `${baseUri}flutter_service_worker.js?v=${serviceWorkerVersion}`,
timeoutMillis = 4000,
} = settings;
// Apply the TrustedTypes policy, if present.
let url = serviceWorkerUrl;
if (this._ttPolicy != null) {
url = this._ttPolicy.createScriptURL(url);
}
const serviceWorkerActivation = navigator.serviceWorker
.register(url)
.then(this._getNewServiceWorker)
.then(this._waitForServiceWorkerActivation);
// Timeout race promise
return timeout(
serviceWorkerActivation,
timeoutMillis,
"prepareServiceWorker"
);
}
/**
* Returns the latest service worker for the given `serviceWorkerRegistrationPromise`.
*
* This might return the current service worker, if there's no new service worker
* awaiting to be installed/updated.
*
* @param {Promise<ServiceWorkerRegistration>} serviceWorkerRegistrationPromise
* @returns {Promise<ServiceWorker>}
*/
async _getNewServiceWorker(serviceWorkerRegistrationPromise) {
const reg = await serviceWorkerRegistrationPromise;
if (!reg.active && (reg.installing || reg.waiting)) {
// No active web worker and we have installed or are installing
// one for the first time. Simply wait for it to activate.
console.debug("Installing/Activating first service worker.");
return reg.installing || reg.waiting;
} else if (!reg.active.scriptURL.endsWith(serviceWorkerVersion)) {
// When the app updates the serviceWorkerVersion changes, so we
// need to ask the service worker to update.
return reg.update().then((newReg) => {
console.debug("Updating service worker.");
return newReg.installing || newReg.waiting || newReg.active;
});
} else {
console.debug("Loading from existing service worker.");
return reg.active;
}
}
/**
* Returns a Promise that resolves when the `latestServiceWorker` changes its
* state to "activated".
*
* @param {Promise<ServiceWorker>} latestServiceWorkerPromise
* @returns {Promise<void>}
*/
async _waitForServiceWorkerActivation(latestServiceWorkerPromise) {
const serviceWorker = await latestServiceWorkerPromise;
if (!serviceWorker || serviceWorker.state == "activated") {
if (!serviceWorker) {
return Promise.reject(
new Error("Cannot activate a null service worker!")
);
} else {
console.debug("Service worker already active.");
return Promise.resolve();
}
}
return new Promise((resolve, _) => {
serviceWorker.addEventListener("statechange", () => {
if (serviceWorker.state == "activated") {
console.debug("Activated new service worker.");
resolve();
}
});
});
}
}
/**
* Handles injecting the main Flutter web entrypoint (main.dart.js), and notifying
* the user when Flutter is ready, through `didCreateEngineInitializer`.
*
* @see https://docs.flutter.dev/development/platform-integration/web/initialization
*/
class FlutterEntrypointLoader {
/**
* Creates a FlutterEntrypointLoader.
*/
constructor() {
// Watchdog to prevent injecting the main entrypoint multiple times.
this._scriptLoaded = false;
}
/**
* Injects a TrustedTypesPolicy (or undefined if the feature is not supported).
* @param {TrustedTypesPolicy | undefined} policy
*/
setTrustedTypesPolicy(policy) {
this._ttPolicy = policy;
}
/**
* Loads flutter main entrypoint, specified by `entrypointUrl`, and calls a
* user-specified `onEntrypointLoaded` callback with an EngineInitializer
* object when it's done.
*
* @param {*} options
* @returns {Promise | undefined} that will eventually resolve with an
* EngineInitializer, or will be rejected with the error caused by the loader.
* Returns undefined when an `onEntrypointLoaded` callback is supplied in `options`.
*/
async loadEntrypoint(options) {
const { entrypointUrl = `${baseUri}main.dart.js`, onEntrypointLoaded } =
options || {};
return this._loadEntrypoint(entrypointUrl, onEntrypointLoaded);
}
/**
* Resolves the promise created by loadEntrypoint, and calls the `onEntrypointLoaded`
* function supplied by the user (if needed).
*
* Called by Flutter through `_flutter.loader.didCreateEngineInitializer` method,
* which is bound to the correct instance of the FlutterEntrypointLoader by
* the FlutterLoader object.
*
* @param {Function} engineInitializer @see https://github.com/flutter/engine/blob/main/lib/web_ui/lib/src/engine/js_interop/js_loader.dart#L42
*/
didCreateEngineInitializer(engineInitializer) {
if (typeof this._didCreateEngineInitializerResolve === "function") {
this._didCreateEngineInitializerResolve(engineInitializer);
// Remove the resolver after the first time, so Flutter Web can hot restart.
this._didCreateEngineInitializerResolve = null;
// Make the engine revert to "auto" initialization on hot restart.
delete _flutter.loader.didCreateEngineInitializer;
}
if (typeof this._onEntrypointLoaded === "function") {
this._onEntrypointLoaded(engineInitializer);
}
}
/**
* Injects a script tag into the DOM, and configures this loader to be able to
* handle the "entrypoint loaded" notifications received from Flutter web.
*
* @param {string} entrypointUrl the URL of the script that will initialize
* Flutter.
* @param {Function} onEntrypointLoaded a callback that will be called when
* Flutter web notifies this object that the entrypoint is
* loaded.
* @returns {Promise | undefined} a Promise that resolves when the entrypoint
* is loaded, or undefined if `onEntrypointLoaded`
* is a function.
*/
_loadEntrypoint(entrypointUrl, onEntrypointLoaded) {
const useCallback = typeof onEntrypointLoaded === "function";
if (!this._scriptLoaded) {
this._scriptLoaded = true;
const scriptTag = this._createScriptTag(entrypointUrl);
if (useCallback) {
// Just inject the script tag, and return nothing; Flutter will call
// `didCreateEngineInitializer` when it's done.
console.debug("Injecting <script> tag. Using callback.");
this._onEntrypointLoaded = onEntrypointLoaded;
document.body.append(scriptTag);
} else {
// Inject the script tag and return a promise that will get resolved
// with the EngineInitializer object from Flutter when it calls
// `didCreateEngineInitializer` later.
return new Promise((resolve, reject) => {
console.debug(
"Injecting <script> tag. Using Promises. Use the callback approach instead!"
);
this._didCreateEngineInitializerResolve = resolve;
scriptTag.addEventListener("error", reject);
document.body.append(scriptTag);
});
}
}
}
/**
* Creates a script tag for the given URL.
* @param {string} url
* @returns {HTMLScriptElement}
*/
_createScriptTag(url) {
const scriptTag = document.createElement("script");
scriptTag.type = "application/javascript";
// Apply TrustedTypes validation, if available.
let trustedUrl = url;
if (this._ttPolicy != null) {
trustedUrl = this._ttPolicy.createScriptURL(url);
}
scriptTag.src = trustedUrl;
return scriptTag;
}
}
/**
* The public interface of _flutter.loader. Exposes two methods:
* * loadEntrypoint (which coordinates the default Flutter web loading procedure)
* * didCreateEngineInitializer (which is called by Flutter to notify that its
* Engine is ready to be initialized)
*/
class FlutterLoader {
/**
* Initializes the Flutter web app.
* @param {*} options
* @returns {Promise?} a (Deprecated) Promise that will eventually resolve
* with an EngineInitializer, or will be rejected with
* any error caused by the loader. Or Null, if the user
* supplies an `onEntrypointLoaded` Function as an option.
*/
async loadEntrypoint(options) {
const { serviceWorker, ...entrypoint } = options || {};
// A Trusted Types policy that is going to be used by the loader.
const flutterTT = new FlutterTrustedTypesPolicy();
// The FlutterServiceWorkerLoader instance could be injected as a dependency
// (and dynamically imported from a module if not present).
const serviceWorkerLoader = new FlutterServiceWorkerLoader();
serviceWorkerLoader.setTrustedTypesPolicy(flutterTT.policy);
await serviceWorkerLoader.loadServiceWorker(serviceWorker).catch(e => {
// Regardless of what happens with the injection of the SW, the show must go on
console.warn("Exception while loading service worker:", e);
});
// The FlutterEntrypointLoader instance could be injected as a dependency
// (and dynamically imported from a module if not present).
const entrypointLoader = new FlutterEntrypointLoader();
entrypointLoader.setTrustedTypesPolicy(flutterTT.policy);
// Install the `didCreateEngineInitializer` listener where Flutter web expects it to be.
this.didCreateEngineInitializer =
entrypointLoader.didCreateEngineInitializer.bind(entrypointLoader);
return entrypointLoader.loadEntrypoint(entrypoint);
}
}
_flutter.loader = new FlutterLoader();
})();