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// This file is part of Moodle - http://moodle.org/
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//
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// Moodle 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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// Moodle 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 Moodle. If not, see <http://www.gnu.org/licenses/>.
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/**
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* Screen reader-only (sr-only) reactive mutations logger class.
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*
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* This logger can be used by the StateManager to log mutation feedbacks and actions.
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* The feedback messages logged by this logger will be rendered in a sr-only, ARIA live region.
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*
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* @module core/local/reactive/srlogger
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* @class SRLogger
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* @copyright 2023 Jun Pataleta <jun@moodle.com>
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* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
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*/
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import Logger from 'core/local/reactive/logger';
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/**
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* Logger entry structure.
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*
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* @typedef {object} LoggerEntry
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* @property {string} feedbackMessage Feedback message.
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*/
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/**
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* Screen reader-only (sr-only) reactive mutations logger class.
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*
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* @class SRLogger
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*/
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export default class SRLogger extends Logger {
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/**
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* The element ID of the ARIA live region where the logger feedback will be rendered.
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*
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* @type {string}
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*/
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static liveRegionId = 'sr-logger-feedback-container';
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/**
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* Add a log entry.
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* @param {LoggerEntry} entry Log entry.
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*/
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add(entry) {
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if (entry.feedbackMessage) {
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// Fetch or create an ARIA live region that will serve as the container for the logger feedback.
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let loggerFeedback = document.getElementById(SRLogger.liveRegionId);
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if (!loggerFeedback) {
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loggerFeedback = document.createElement('div');
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loggerFeedback.id = SRLogger.liveRegionId;
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loggerFeedback.classList.add('sr-only');
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loggerFeedback.setAttribute('aria-live', 'polite');
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document.body.append(loggerFeedback);
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}
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// Set the ARIA live region's contents with the feedback.
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loggerFeedback.innerHTML = entry.feedbackMessage;
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// Clear the feedback message after 4 seconds to avoid the contents from being read out in case the user navigates
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// to this region. This is similar to the default timeout of toast messages before disappearing from view.
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setTimeout(() => {
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loggerFeedback.innerHTML = '';
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}, 4000);
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}
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}
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}
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