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| 1 | +/* |
| 2 | + * This file is part of the QuestionPy Moodle plugin - https://questionpy.org |
| 3 | + * |
| 4 | + * Moodle is free software: you can redistribute it and/or modify |
| 5 | + * it under the terms of the GNU General Public License as published by |
| 6 | + * the Free Software Foundation, either version 3 of the License, or |
| 7 | + * (at your option) any later version. |
| 8 | + * |
| 9 | + * Moodle is distributed in the hope that it will be useful, |
| 10 | + * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 11 | + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 12 | + * GNU General Public License for more details. |
| 13 | + * |
| 14 | + * You should have received a copy of the GNU General Public License |
| 15 | + * along with Moodle. If not, see <http://www.gnu.org/licenses/>. |
| 16 | + */ |
| 17 | + |
| 18 | +import $ from "jquery"; |
| 19 | +import "theme_boost/bootstrap/popover"; |
| 20 | + |
| 21 | +/** |
| 22 | + * If the given input(-like) element is labelled, returns the label element. Returns null otherwise. |
| 23 | + * |
| 24 | + * @param {HTMLElement} input |
| 25 | + * @return {HTMLLabelElement | null} |
| 26 | + * @see {@link https://html.spec.whatwg.org/multipage/forms.html#the-label-element} |
| 27 | + */ |
| 28 | +function getLabelFor(input) { |
| 29 | + // A label can reference its labeled control in its for attribute. |
| 30 | + const id = input.id; |
| 31 | + if (id !== "") { |
| 32 | + const label = document.querySelector(`label[for='${id}']`); |
| 33 | + if (label) { |
| 34 | + return label; |
| 35 | + } |
| 36 | + } |
| 37 | + |
| 38 | + // Or the labeled control can be a descendant of the label. |
| 39 | + const label = input.closest("label"); |
| 40 | + if (label) { |
| 41 | + return label; |
| 42 | + } |
| 43 | + |
| 44 | + return null; |
| 45 | +} |
| 46 | + |
| 47 | +/** |
| 48 | + * Marks the given input element as invalid. |
| 49 | + * |
| 50 | + * @param {HTMLElement} element |
| 51 | + * @param {string} message validation message to show |
| 52 | + * @param {boolean} ariaInvalid |
| 53 | + */ |
| 54 | +function markInvalid(element, message, ariaInvalid = true) { |
| 55 | + element.classList.add("is-invalid"); |
| 56 | + if (ariaInvalid) { |
| 57 | + element.setAttribute("aria-invalid", "true"); |
| 58 | + } else { |
| 59 | + element.removeAttribute("aria-invalid"); |
| 60 | + } |
| 61 | + |
| 62 | + let popoverTarget = element; |
| 63 | + if (element.type === "checkbox" || element.type === "radio") { |
| 64 | + // Checkboxes and radios make for a very small hit area for the popover, so we attach the popover to the label. |
| 65 | + const label = getLabelFor(element); |
| 66 | + if (!label) { |
| 67 | + // No label -> Add the popover just to the checkbox. |
| 68 | + popoverTarget = element; |
| 69 | + } else if (label.contains(element)) { |
| 70 | + // Label contains checkbox -> Add the popover just to the label. |
| 71 | + popoverTarget = label; |
| 72 | + } else { |
| 73 | + // Separate label and checkbox -> Add the popover to both. |
| 74 | + popoverTarget = [element, label]; |
| 75 | + } |
| 76 | + } |
| 77 | + |
| 78 | + $(popoverTarget).popover({ |
| 79 | + toggle: "popover", |
| 80 | + trigger: "hover", |
| 81 | + content: message |
| 82 | + }); |
| 83 | +} |
| 84 | + |
| 85 | +/** |
| 86 | + * Undoes what {@link markInvalid} did. |
| 87 | + * |
| 88 | + * @param {HTMLInputElement} element |
| 89 | + */ |
| 90 | +function unmarkInvalid(element) { |
| 91 | + element.classList.remove("is-invalid"); |
| 92 | + element.removeAttribute("aria-invalid"); |
| 93 | + |
| 94 | + $([element, getLabelFor(element)]).popover("dispose"); |
| 95 | +} |
| 96 | + |
| 97 | +/** |
| 98 | + * Softly (i.e. without preventing form submission) validates constraints on the given element. |
| 99 | + * |
| 100 | + * @param {HTMLInputElement} element |
| 101 | + */ |
| 102 | +async function checkConstraints(element) { |
| 103 | + /* Our goal here is to show helpful localised validation messages without actually preventing form submission. |
| 104 | + One way to achieve this would be to add the attribute "novalidate" to the form element, but that might interfere |
| 105 | + with other questions (since they share the same form). |
| 106 | + We also don't want to reimplement the validation logic already implemented by browsers. |
| 107 | + Instead, the standard validation attributes are added, their validity checked, the message used to create a |
| 108 | + popover, and the attributes removed. */ |
| 109 | + try { |
| 110 | + if ("qpy_required" in element.dataset) { |
| 111 | + element.setAttribute("required", "required"); |
| 112 | + } |
| 113 | + for (const attr of ["pattern", "minlength", "maxlength", "min", "max"]) { |
| 114 | + if (`qpy_${attr}` in element.dataset) { |
| 115 | + element.setAttribute(attr, element.dataset[`qpy_${attr}`]); |
| 116 | + } |
| 117 | + } |
| 118 | + |
| 119 | + const isValid = element.checkValidity(); |
| 120 | + if (isValid) { |
| 121 | + unmarkInvalid(element); |
| 122 | + } else { |
| 123 | + // Aria-invalid shouldn't be set for missing inputs until the user has tried to submit them. |
| 124 | + // https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/Attributes/aria-invalid |
| 125 | + markInvalid(element, element.validationMessage, !element.validity.valueMissing); |
| 126 | + } |
| 127 | + } finally { |
| 128 | + for (const attr of ["required", "pattern", "minlength", "maxlength", "min", "max"]) { |
| 129 | + element.removeAttribute(attr); |
| 130 | + } |
| 131 | + } |
| 132 | +} |
| 133 | + |
| 134 | +/** |
| 135 | + * Adds change event handlers for soft validation. |
| 136 | + */ |
| 137 | +export async function init() { |
| 138 | + for (const element of document.querySelectorAll(` |
| 139 | + [data-qpy_required], [data-qpy_pattern], |
| 140 | + [data-qpy_minlength], [data-qpy_maxlength], |
| 141 | + [data-qpy_min], [data-qpy_max] |
| 142 | + `)) { |
| 143 | + await checkConstraints(element); |
| 144 | + element.addEventListener("change", event => checkConstraints(event.target)); |
| 145 | + } |
| 146 | +} |
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