bigbluebutton-Github/bigbluebutton-html5/imports/ui/services/virtual-background/TimeWorker.js

/* NOTICE: This file is a Derivative Work of the original component in Jitsi Meet
 * See https://github.com/jitsi/jitsi-meet/tree/master/react/features/stream-effects/virtual-background/vendor.
 * It is copied under the Apache Public License 2.0 (see https://www.apache.org/licenses/LICENSE-2.0).
 */

/**
 * SET_TIMEOUT constant is used to set interval and it is set in
 * the id property of the request.data property. timeMs property must
 * also be set. request.data example:
 *
 * {
 *      id: SET_TIMEOUT,
 *      timeMs: 33
 * }
 */
 export const SET_TIMEOUT = 1;

 /**
  * CLEAR_TIMEOUT constant is used to clear the interval and it is set in
  * the id property of the request.data property.
  *
  * {
  *      id: CLEAR_TIMEOUT
  * }
  */
 export const CLEAR_TIMEOUT = 2;

 /**
  * TIMEOUT_TICK constant is used as response and it is set in the id property.
  *
  * {
  *      id: TIMEOUT_TICK
  * }
  */
 export const TIMEOUT_TICK = 3;

 /**
  * The following code is needed as string to create a URL from a Blob.
  * The URL is then passed to a WebWorker. Reason for this is to enable
  * use of setInterval that is not throttled when tab is inactive.
  */
 const code = `
     var timer;
     onmessage = function(request) {
         switch (request.data.id) {
         case ${SET_TIMEOUT}: {
             timer = setTimeout(() => {
                 postMessage({ id: ${TIMEOUT_TICK} });
             }, request.data.timeMs);
             break;
         }
         case ${CLEAR_TIMEOUT}: {
             if (timer) {
                 clearTimeout(timer);
             }
             break;
         }
         }
     };
 `;

 export const timerWorkerScript = URL.createObjectURL(new Blob([ code ], { type: 'application/javascript' }));