{"version":3,"file":"scroll_manager.min.js","sources":["../src/scroll_manager.js"],"sourcesContent":["// This file is part of Moodle - http://moodle.org/\n//\n// Moodle is free software: you can redistribute it and/or modify\n// it under the terms of the GNU General Public License as published by\n// the Free Software Foundation, either version 3 of the License, or\n// (at your option) any later version.\n//\n// Moodle is distributed in the hope that it will be useful,\n// but WITHOUT ANY WARRANTY; without even the implied warranty of\n// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the\n// GNU General Public License for more details.\n//\n// You should have received a copy of the GNU General Public License\n// along with Moodle. If not, see <http://www.gnu.org/licenses/>.\n\n/**\n * Scroll manager is a class that help with saving the scroll positing when you\n * click on an action icon, and then when the page is reloaded after processing\n * the action, it scrolls you to exactly where you were. This is much nicer for\n * the user.\n *\n * To use this in your code, you need to ensure that:\n * 1. The button that triggers the action has to have a click event handler that\n * calls saveScrollPos()\n * 2. After doing the processing, the redirect() function will add 'mdlscrollto'\n * parameter into the redirect url automatically.\n * 3. Finally, on the page that is reloaded (which should be the same as the one\n * the user started on) you need to call scrollToSavedPosition()\n * on page load.\n *\n * @module core/scroll_manager\n * @copyright 2021 The Open University\n * @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later\n */\n\n/** @property {HTMLElement} scrollingElement the current scrolling element. */\nlet scrollingElement = null;\n\n/**\n * Is the element scrollable?\n *\n * @param {HTMLElement} element Element.\n * @returns {boolean}\n */\nconst isScrollable = (element) => {\n // Check if the element has scrollable content.\n const hasScrollableContent = element.scrollHeight > element.clientHeight;\n\n // If 'overflow-y' is set to hidden, the scroll bar is't show.\n const elementOverflow = window.getComputedStyle(element).overflowY;\n const isOverflowHidden = elementOverflow.indexOf('hidden') !== -1;\n\n return hasScrollableContent && !isOverflowHidden;\n};\n\n/**\n * Get the scrolling element.\n *\n * @returns {HTMLElement}\n */\nconst getScrollingElement = () => {\n if (scrollingElement === null) {\n const page = document.getElementById('page');\n if (isScrollable(page)) {\n scrollingElement = page;\n } else {\n scrollingElement = document.scrollingElement;\n }\n }\n\n return scrollingElement;\n};\n\n/**\n * Get current scroll position.\n *\n * @returns {Number} Scroll position.\n */\nconst getScrollPos = () => {\n const scrollingElement = getScrollingElement();\n\n return scrollingElement.scrollTop;\n};\n\n/**\n * Get the scroll position for this form.\n *\n * @param {HTMLFormElement} form\n * @returns {HTMLInputElement}\n */\nconst getScrollPositionElement = (form) => {\n const element = form.querySelector('input[name=mdlscrollto]');\n if (element) {\n return element;\n }\n\n const scrollPos = document.createElement('input');\n scrollPos.type = 'hidden';\n scrollPos.name = 'mdlscrollto';\n form.appendChild(scrollPos);\n\n return scrollPos;\n};\n\n/**\n * In the form that contains the element, set the value of the form field with\n * name mdlscrollto to the current scroll position. If there is no element with\n * that name, it creates a hidden form field with that name within the form.\n *\n * @param {string} elementId The element in the form.\n */\nexport const saveScrollPos = (elementId) => {\n const element = document.getElementById(elementId);\n const form = element.closest('form');\n if (!form) {\n return;\n }\n\n saveScrollPositionToForm(form);\n};\n\n/**\n * Init event handlers for all links with data-savescrollposition=true.
