mirror of
https://github.com/element-hq/element-web
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125 lines
3.5 KiB
JavaScript
125 lines
3.5 KiB
JavaScript
/*
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Copyright 2018 New Vector Ltd
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/**
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A countdown timer, exposing a promise api.
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A timer starts in a non-started state,
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and needs to be started by calling `start()`` on it first.
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Timers can be `abort()`-ed which makes the promise reject prematurely.
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Once a timer is finished or aborted, it can't be started again
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(because the promise should not be replaced). Instead, create
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a new one through `clone()` or `cloneIfRun()`.
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*/
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export default class Timer {
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constructor(timeout) {
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this._timeout = timeout;
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this._onTimeout = this._onTimeout.bind(this);
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this._setNotStarted();
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}
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_setNotStarted() {
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this._timerHandle = null;
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this._startTs = null;
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this._promise = new Promise((resolve, reject) => {
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this._resolve = resolve;
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this._reject = reject;
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}).finally(() => {
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this._timerHandle = null;
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});
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}
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_onTimeout() {
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const now = Date.now();
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const elapsed = now - this._startTs;
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if (elapsed >= this._timeout) {
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this._resolve();
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this._setNotStarted();
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} else {
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const delta = this._timeout - elapsed;
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this._timerHandle = setTimeout(this._onTimeout, delta);
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}
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}
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changeTimeout(timeout) {
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if (timeout === this._timeout) {
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return;
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}
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const isSmallerTimeout = timeout < this._timeout;
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this._timeout = timeout;
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if (this.isRunning() && isSmallerTimeout) {
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clearTimeout(this._timerHandle);
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this._onTimeout();
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}
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}
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/**
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* if not started before, starts the timer.
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* @returns {Timer} the same timer
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*/
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start() {
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if (!this.isRunning()) {
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this._startTs = Date.now();
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this._timerHandle = setTimeout(this._onTimeout, this._timeout);
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}
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return this;
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}
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/**
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* (re)start the timer. If it's running, reset the timeout. If not, start it.
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* @returns {Timer} the same timer
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*/
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restart() {
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if (this.isRunning()) {
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// don't clearTimeout here as this method
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// can be called in fast succession,
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// instead just take note and compare
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// when the already running timeout expires
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this._startTs = Date.now();
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return this;
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} else {
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return this.start();
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}
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}
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/**
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* if the timer is running, abort it,
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* and reject the promise for this timer.
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* @returns {Timer} the same timer
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*/
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abort() {
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if (this.isRunning()) {
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clearTimeout(this._timerHandle);
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this._reject(new Error("Timer was aborted."));
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this._setNotStarted();
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}
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return this;
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}
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/**
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*promise that will resolve when the timer elapses,
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*or is rejected when abort is called
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*@return {Promise}
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*/
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finished() {
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return this._promise;
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}
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isRunning() {
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return this._timerHandle !== null;
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}
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}
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