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visibilityChangeListener

Waits until the tab is focused, executing a callback function when it happens.

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greasyfork.ip-ddns.com/scripts/480373/1283462/visibilityChangeListener.js 

// ==UserScript==
// @name         visibilityChangeListener
// @namespace    http://tampermonkey.net/
// @version      0.2
// @description  Waits until the tab is focused, executing a callback function when it happens.
// @author       IgnaV
// @grant        none
// ==/UserScript==

const visibilityChangeListener = (onFocus, onBlur, minTime = 0) => {
    let lastExecutionFocusTime = 0;
    let lastExecutionBlurTime = 0;

    document.addEventListener('visibilitychange', function () {
        const currentTime = Date.now();

        if (document.visibilityState === 'visible') {
            if (onFocus && currentTime - lastExecutionFocusTime >= minTime) {
                onFocus();
                lastExecutionFocusTime = currentTime;
            }
        } else if (onBlur && currentTime - lastExecutionBlurTime >= minTime) {
            onBlur();
            lastExecutionBlurTime = currentTime;
        }
    });
};