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// This file is part of Moodle - http://moodle.org/
//
// Moodle is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Moodle is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Moodle. If not, see <http://www.gnu.org/licenses/>.
/**
* Submit button JavaScript. All submit buttons will be automatically disabled once the form is
* submitted, unless that submission results in an error/cancelling the submit.
*
* @module core_form/submit
* @copyright 2019 The Open University
* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
* @since 3.8
*/
import {eventTypes} from 'core_form/events';
/** @property {number} ID for setInterval used when polling for download cookie */
let cookieListener = 0;
/** @property {Array} Array of buttons that need re-enabling if we get a download cookie */
const cookieListeningButtons = [];
/** @property {number} Number of files uploading. */
let currentUploadCount = 0;
/** @property {Array} Array of buttons that need re-enabling if we get a upload process. */
const uploadListeningButtons = [];
/** @property {Boolean} Is upload listeners registered? */
let uploadListenersRegistered = false;
/**
* Listens in case a download cookie is provided.
*
* This function is used to detect file downloads. If there is a file download then we get a
* beforeunload event, but the page is never unloaded and when the file download completes we
* should re-enable the buttons. We detect this by watching for a specific cookie.
*
* PHP function \core_form\util::form_download_complete() can be used to send this cookie.
*
* @param {HTMLElement} button Button to re-enable
*/
const listenForDownloadCookie = (button) => {
cookieListeningButtons.push(button);
if (!cookieListener) {
cookieListener = setInterval(() => {
// Look for cookie.
const parts = document.cookie.split(getCookieName() + '=');
if (parts.length == 2) {
// We found the cookie, so the file is ready. Expire the cookie and cancel polling.
clearDownloadCookie();
clearInterval(cookieListener);
cookieListener = 0;
// Re-enable all the buttons.
cookieListeningButtons.forEach((button) => {
button.disabled = false;
});
}
}, 500);
}
};
/**
* Gets a unique name for the download cookie.
*
* @returns {string} Cookie name
*/
const getCookieName = () => {
return 'moodledownload_' + M.cfg.sesskey;
};
/**
* Clears the download cookie if there is one.
*/
const clearDownloadCookie = () => {
document.cookie = encodeURIComponent(getCookieName()) + '=deleted; expires=' + new Date(0).toUTCString();
};
/**
* Enable submit buttons when all files are uploaded.
*/
const checkUploadCount = () => {
if (currentUploadCount) {
uploadListeningButtons.forEach(button => {
button.disabled = true;
});
} else {
uploadListeningButtons.forEach(button => {
button.disabled = false;
});
}
};
/**
* Initialises submit buttons.
*
* @param {String} elementId Form button element
* @listens event:uploadStarted
* @listens event:uploadCompleted
*/
export const init = (elementId) => {
const button = document.getElementById(elementId);
if (button === null) {
// Exit early if invalid element id passed.
return;
}
// If buttons are disabled by default, we do not enable them when file upload completed event is fired.
if (!button.disabled) {
uploadListeningButtons.push(button);
}
if (!uploadListenersRegistered) {
// Add event listener for file upload start.
document.addEventListener(eventTypes.uploadStarted, () => {
currentUploadCount++;
checkUploadCount();
});
// Add event listener for file upload complete.
document.addEventListener(eventTypes.uploadCompleted, () => {
currentUploadCount--;
checkUploadCount();
});
uploadListenersRegistered = true;
}
// If the form has double submit protection disabled, do nothing.
if (button.form.dataset.doubleSubmitProtection === 'off') {
return;
}
button.form.addEventListener('submit', function(event) {
// Only disable it if the browser is really going to another page as a result of the
// submit.
const disableAction = function() {
// If the submit was cancelled, or the button is already disabled, don't do anything.
if (event.defaultPrevented || button.disabled) {
return;
}
button.disabled = true;
clearDownloadCookie();
listenForDownloadCookie(button);
};
window.addEventListener('beforeunload', disableAction);
// If there is no beforeunload event as a result of this form submit, then the form
// submit must have been cancelled, so don't disable the button if the page is
// unloaded later.
setTimeout(function() {
window.removeEventListener('beforeunload', disableAction);
}, 0);
}, false);
};
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