Reimplement the multiselect as a custom element
What i really set off on was to refactor the multiselect’s x-data context to a separate JavaScript file. I did not see the need at first, thinking that it would not matter because it was used only in a template and i was not duplicating the code in my files. However, i then realized that having the context in the template means the visitor has to download it each and every time it accesses a form with a multiselect, even if nothing changed, and, worse, it would download it multiple times if there were many multiselect controls. It makes more sense to put all that into a file that the browser would only download and parse once, if the proper caching is set. Once i realized that, it was a shame that AlpineJS has no way to do the same for the HTML structure[0], for the exact same reasons: not wanting to download many times the same extra <template> and other markup required to build the control for JavaScript users. And then i remembered that this is supposed to be custom element’s main selling point. At first i tried to create a shadow DOW to replace the <select> with the same <div> and <ul> that i used with Alpine, but it turns out that <select> is not one of the allowed elements that can have a shadow root attached[0]. Therefore, i changed the custom element to extend the <div> for the <select> and <label> instead—the same element that had the x-init context—, but i would have to define or include all the styles inside the shadow DOM, and bring the lang attribute, for it to look like it did before. Out with the shadow DOM, and modify the <div>’s contents instead. At this point the code was so far removed from the declarative way that AlpineJS promotes that i did not see much value on using it, except for its reactivity. But, given that this is such a small component, at the end decided to write it all in plain JavaScript. It is more code, at least looking only at the code i had to write, but i love how i only have to add an is="numerus-multiselect" attribute to HTML for it to work. [0]: https://github.com/alpinejs/alpine/discussions/1205 [1]: https://developer.mozilla.org/en-US/docs/Web/API/Element/attachShadow
This commit is contained in:
parent
1c9fe14ab9
commit
2dde25c862
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@ -589,11 +589,11 @@ main > nav {
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}
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/* Multiselect */
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.multiselect {
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[is="numerus-multiselect"] {
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max-width: 35rem;
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}
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.multiselect .tags, .multiselect .options {
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[is="numerus-multiselect"] .tags, [is="numerus-multiselect"] .options {
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font-size: 1em;
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list-style: none;
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color: var(--numerus--text-color);
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@ -602,7 +602,7 @@ main > nav {
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border-radius: 0;
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}
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.multiselect .tags {
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[is="numerus-multiselect"] .tags {
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display: flex;
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flex-wrap: wrap;
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gap: 1rem;
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@ -613,7 +613,7 @@ main > nav {
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min-width: 20rem;
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}
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.multiselect .tags:after {
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[is="numerus-multiselect"] .tags:after {
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content: '';
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border-top: 6px solid black;
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border-left: 6px solid transparent;
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@ -625,22 +625,22 @@ main > nav {
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cursor: pointer;
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}
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.multiselect .tag {
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[is="numerus-multiselect"] .tag {
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background-color: var(--numerus--color--hay);
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}
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.multiselect .tag button {
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[is="numerus-multiselect"] .tag button {
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border: none;
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cursor: pointer;
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background: transparent;
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min-width: initial;
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}
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.multiselect .tag button:hover {
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[is="numerus-multiselect"] .tag button:hover {
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background: rgba(255, 255, 255, .4);
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}
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.multiselect .tags input {
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[is="numerus-multiselect"] .tags input {
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flex: 1;
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width: 100%;
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border: 0;
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@ -651,22 +651,23 @@ main > nav {
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appearance: none;
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}
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.multiselect .options {
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[is="numerus-multiselect"] .options {
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padding: 0;
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border-top: 0;
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position: absolute;
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left: 0;
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right: 0;
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z-index: 10;
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}
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.multiselect .options li {
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[is="numerus-multiselect"] .options li {
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display: block;
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width: 100%;
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cursor: pointer;
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padding: 1rem 2rem;
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}
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.multiselect .options li:hover {
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[is="numerus-multiselect"] .options li:hover {
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background-color: var(--numerus--color--light-gray);
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}
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@ -0,0 +1,203 @@
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class Multiselect extends HTMLDivElement {
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constructor() {
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super();
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this.initialized = false;
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this.toSearch = '';
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}
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connectedCallback() {
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if (!this.initialized) {
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for (const child of this.children) {
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switch (child.nodeName) {
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case 'SELECT':
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this.select = child;
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break;
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case 'LABEL':
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this.label = child;
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break;
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}
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}
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if (this.label && this.select) {
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this.init();
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}
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}
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}
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init() {
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this.initialized = true;
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this.select.style.display = 'none';
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for (const option of this.select.options) {
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option.dataset.numerusSearch = Multiselect.normalize(option.textContent);
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}
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this.tags = document.createElement('div');
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this.append(this.tags);
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this.tags.classList.add('tags');
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this.tags.addEventListener('click', () => this.toggle());
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this.search = document.createElement('input');
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this.tags.append(this.search);
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this.search.id = this.select.id;
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this.select.removeAttribute('id');
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this.search.addEventListener('input', (e) => {
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this.open();
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this.filter(e.target.value);
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});
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this.search.addEventListener('keydown', (e) => {
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switch (e.code) {
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case "Enter":
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e.preventDefault();
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this.selectFirst();
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break;
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case "Backspace":
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if (e.target.value === '') {
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this.deselectLast();
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}
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break;
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case "Escape":
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this.close();
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break;
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}
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});
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// Must come after the search input
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this.tags.append(this.label);
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this.options = document.createElement('ul');
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this.append(this.options);
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this.options.classList.add('options');
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this.close();
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window.addEventListener('focusin', (e) => {
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if (this.contains(e.target)) return;
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this.close();
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});
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document.addEventListener('click', (e) => {
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if (this.contains(e.target)) return;
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if (!e.target.isConnected) return;
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this.close();
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});
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this.rebuild();
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}
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rebuildOptions() {
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this.options.innerHTML = '';
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for (const option of this.select.options) {
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if (!this.isOptionSelectable(option)) {
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continue;
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}
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const li = document.createElement('li');
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this.options.append(li);
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li.textContent = option.textContent;
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li.addEventListener('click', () => this.selectOption(option, true));
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}
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}
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isOptionSelectable(option) {
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if (option.selected) {
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return false;
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}
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return this.toSearch === '' || option.dataset.numerusSearch.includes(this.toSearch);
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}
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selectOption(option, selected) {
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option.selected = selected;
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this.toSearch = this.search.value = '';
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this.rebuild();
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}
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selectFirst() {
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if (!this.isOpen()) {
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return;
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}
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for (const option of this.select.options) {
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if (this.isOptionSelectable(option)) {
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this.selectOption(option, true);
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break;
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}
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}
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}
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deselectLast() {
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const options = this.select.options;
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for (let i = options.length - 1; i >= 0; i--) {
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const option = options[i];
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if (option.selected) {
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this.selectOption(option, false);
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break;
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}
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}
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}
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rebuild() {
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this.rebuildTags();
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this.rebuildOptions();
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}
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rebuildTags() {
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this.tags.querySelectorAll('.tag').forEach((tag) => tag.remove());
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let empty = true;
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for (const option of this.select.options) {
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if (!option.selected) {
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continue;
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}
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empty = false;
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const tag = document.createElement('div');
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this.tags.insertBefore(tag, this.search);
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tag.classList.add('tag');
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tag.dataset.numerusSearch = option.dataset.numerusSearch;
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const span = document.createElement('span');
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tag.append(span);
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span.textContent = option.textContent;
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const button = document.createElement('button');
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tag.append(button);
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button.type = 'button';
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button.textContent = '×';
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button.addEventListener('click', (e) => {
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e.stopPropagation();
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this.selectOption(option, false)
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});
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}
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if (empty) {
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this.search.setAttribute('placeholder', this.label.textContent);
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} else {
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this.search.removeAttribute('placeholder');
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}
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}
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close() {
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this.options.style.display = 'none';
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}
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open() {
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this.options.removeAttribute('style');
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}
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toggle() {
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if (this.isOpen()) {
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this.close();
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} else {
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this.open();
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}
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}
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isOpen() {
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return !this.options.hasAttribute('style');
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}
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filter(search) {
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this.toSearch = Multiselect.normalize(search);
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this.rebuildOptions()
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}
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static normalize(s) {
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return s.normalize('NFD').replace(/\p{Diacritic}/gu, '').toLowerCase().trim();
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}
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}
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customElements.define('numerus-multiselect', Multiselect, {extends: 'div'});
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@ -5,7 +5,7 @@
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<meta name="viewport" content="width=device-width, initial-scale=1">
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<title>{{ template "title" . }} — Numerus</title>
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<link rel="stylesheet" type="text/css" media="screen" href="/static/numerus.css">
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<script defer src="/static/alpinejs@3.12.0.min.js"></script>
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<script type="module" src="/static/numerus.js"></script>
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</head>
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<body>
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<header>
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@ -40,81 +40,7 @@
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{{ define "select-field" -}}
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{{- /*gotype: dev.tandem.ws/tandem/numerus/pkg.SelectField*/ -}}
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<div class="input{{ if .Errors }} has-errors{{ end }}"
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{{- if .Multiple }}
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@focusin.window="! $el.contains($event.target) && close() "
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@click.away="close()"
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x-data="{
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options: [],
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name: '',
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filter: '',
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open: false,
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init() {
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const select = $el.querySelector('select');
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this.name = select.name;
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for (const option of select.options) {
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this.options.push({
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value: option.value,
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label: option.innerText,
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search: this.normalize(option.innerText),
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selected: option.getAttribute('selected') !== null,
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});
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}
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select.remove();
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const template = $el.querySelector('template');
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const input = template.content.querySelector('input');
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const label = $el.querySelector('label');
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input.after(label);
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},
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selected() {
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return this.options.filter(option => option.selected);
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},
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normalize(s) {
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return s.normalize('NFD').replace(/\p{Diacritic}/gu, '').toLowerCase();
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},
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unselected() {
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const filter = this.normalize(this.filter);
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return this.options.filter(option => !option.selected && (filter === '' || option.search.includes(filter)));
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},
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empty() {
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return this.selected().length === 0;
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},
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selectOption(option) {
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option.selected = true;
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this.filter = '';
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},
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selectFirst() {
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if (!this.open) {
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return;
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}
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const all = this.unselected();
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if (all.length === 0) {
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return;
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}
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this.selectOption(all[0]);
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},
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unselectLast() {
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if (this.filter !== '') {
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return;
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}
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const all = this.selected();
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if (all.length === 0) {
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return;
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}
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all[all.length - 1].selected = false;
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},
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toggle() {
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if (this.open) {
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return this.close();
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}
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this.open = true;
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},
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close() {
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this.open = false;
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},
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}"
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{{- end -}}
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>
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<div class="input{{ if .Errors }} has-errors{{ end }}"{{ if .Multiple }} is="numerus-multiselect"{{ end -}}>
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<select id="{{ .Name }}-field" name="{{ .Name }}"
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{{- range $attribute := .Attributes }} {{$attribute}} {{ end -}}
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{{ if .Multiple }} multiple="multiple"{{ end -}}
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@ -139,37 +65,6 @@
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</optgroup>
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{{- end }}
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</select>
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{{- if .Multiple }}
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<template x-if="true">
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<div class="multiselect">
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<div class="tags" :class="{'empty': empty()}"
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@click="toggle()"
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>
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<template x-for="option in selected()">
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<div class="tag">
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<input type="hidden" :name="name" :value="option.value">
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<span x-text="option.label"></span>
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<button type="button" @click.stop="option.selected = false">×</button>
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</div>
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</template>
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<input id="{{ .Name }}-field" :placeholder="empty() && '{{ .Label }}'" x-model="filter"
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@input="open = true"
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@keydown.escape="close()"
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@keydown.prevent.enter="selectFirst()"
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@keydown.backspace="unselectLast()"
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>
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</div>
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<ul class="options" x-show.transition="open">
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<template x-for="option in unselected()">
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<li
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x-text="option.label"
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@click.stop="selectOption(option)"
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></li>
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</template>
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</ul>
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</div>
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</template>
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{{ end -}}
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<label for="{{ .Name }}-field">{{ .Label }}</label>
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{{- if .Errors }}
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<ul>
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Reference in New Issue