61 lines
1.7 KiB
JavaScript
61 lines
1.7 KiB
JavaScript
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/*
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* Copyright (C) 2019 Alex Yatskov <alex@foosoft.net>
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* Author: Alex Yatskov <alex@foosoft.net>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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class PageExitPrevention {
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constructor() {
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}
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start() {
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PageExitPrevention._addInstance(this);
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}
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end() {
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PageExitPrevention._removeInstance(this);
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}
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static _addInstance(instance) {
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const size = PageExitPrevention._instances.size;
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PageExitPrevention._instances.set(instance, true);
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if (size === 0) {
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window.addEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
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}
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}
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static _removeInstance(instance) {
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if (
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PageExitPrevention._instances.delete(instance) &&
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PageExitPrevention._instances.size === 0
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) {
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window.removeEventListener('beforeunload', PageExitPrevention._onBeforeUnload);
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}
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}
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static _onBeforeUnload(e) {
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if (PageExitPrevention._instances.size === 0) {
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return;
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}
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e.preventDefault();
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e.returnValue = '';
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return '';
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}
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}
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PageExitPrevention._instances = new Map();
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