tor-browser

The Tor Browser
git clone https://git.dasho.dev/tor-browser.git
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debounce.js (2470B)

      1 /* This Source Code Form is subject to the terms of the Mozilla Public
      2 * License, v. 2.0. If a copy of the MPL was not distributed with this
      3 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
      4 "use strict";
      5 
      6 /**
      7 * Redux middleware for debouncing actions.
      8 *
      9 * Schedules actions with { meta: { debounce: true } } to be delayed
     10 * by wait milliseconds. If another action is fired during this
     11 * time-frame both actions are inserted into a queue and delayed.
     12 * Maximum delay is defined by maxWait argument.
     13 *
     14 * Handling more actions at once results in better performance since
     15 * components need to be re-rendered less often.
     16 *
     17 * @param string wait Wait for specified amount of milliseconds
     18 *                    before executing an action. The time is used
     19 *                    to collect more actions and handle them all
     20 *                    at once.
     21 * @param string maxWait Max waiting time. It's used in case of
     22 *                       a long stream of actions.
     23 */
     24 function debounceActions(wait, maxWait) {
     25  let queuedActions = [];
     26 
     27  return () => next => {
     28    const debounced = debounce(
     29      () => {
     30        next(batchActions(queuedActions));
     31        queuedActions = [];
     32      },
     33      wait,
     34      maxWait
     35    );
     36 
     37    return action => {
     38      if (!action.meta || !action.meta.debounce) {
     39        return next(action);
     40      }
     41 
     42      if (!wait || !maxWait) {
     43        return next(action);
     44      }
     45 
     46      if (action.type == BATCH_ACTIONS) {
     47        queuedActions.push(...action.actions);
     48      } else {
     49        queuedActions.push(action);
     50      }
     51 
     52      return debounced();
     53    };
     54  };
     55 }
     56 
     57 function debounce(cb, wait, maxWait) {
     58  let timeout, maxTimeout;
     59  const doFunction = () => {
     60    clearTimeout(timeout);
     61    clearTimeout(maxTimeout);
     62    timeout = maxTimeout = null;
     63    cb();
     64  };
     65 
     66  return () => {
     67    return new Promise(resolve => {
     68      const onTimeout = () => {
     69        doFunction();
     70        resolve();
     71      };
     72 
     73      clearTimeout(timeout);
     74 
     75      timeout = setTimeout(onTimeout, wait);
     76      if (!maxTimeout) {
     77        maxTimeout = setTimeout(onTimeout, maxWait);
     78      }
     79    });
     80  };
     81 }
     82 
     83 const BATCH_ACTIONS = Symbol("BATCH_ACTIONS");
     84 
     85 /**
     86 * Action creator for action-batching.
     87 */
     88 function batchActions(batchedActions, debounceFlag = true) {
     89  return {
     90    type: BATCH_ACTIONS,
     91    meta: { debounce: debounceFlag },
     92    actions: batchedActions,
     93  };
     94 }
     95 
     96 module.exports = {
     97  BATCH_ACTIONS,
     98  batchActions,
     99  debounceActions,
    100 };