Created
February 27, 2021 17:47
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A custom element for rendering a checkbox list
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/** | |
* A custom element for rendering a checkbox list of items. Example: | |
* <checkbox-list | |
* title="Hello World" | |
* itemLabels="Apple,Banana, Chocolate" | |
* items="a,b,c" | |
* value="all" | |
* /> | |
* | |
* And change can be detected with: | |
* const element = document.querySelector('checkbox-list'); | |
* element.addEventListener('change', (evt) => { | |
* console.log(evt.target.value); | |
* }); | |
*/ | |
class CheckboxList extends HTMLElement { | |
constructor() { | |
super(); | |
this.container = document.createElement("div"); | |
} | |
static get observedAttributes() { | |
return ["itemLabels", "items", "value"]; | |
} | |
get title() { | |
return this.getAttribute("title"); | |
} | |
set title(value) { | |
this.setAttribute("title", value); | |
} | |
get itemLabels() { | |
return this.getAttribute("itemLabels") | |
.split(",") | |
.map((s) => s.trim()); | |
} | |
set itemLabels(value) { | |
this.setAttribute("itemLabels", value); | |
} | |
get items() { | |
return this.getAttribute("items") | |
.split(",") | |
.map((s) => s.trim()); | |
} | |
set items(value) { | |
this.setAttribute("items", value); | |
} | |
get value() { | |
if (this.getAttribute("value") === "all") { | |
return this.items; | |
} | |
if (this.getAttribute("value").trim() === "") { | |
return []; | |
} | |
return this.getAttribute("value") | |
.split(",") | |
.map((s) => s.trim()); | |
} | |
set value(value) { | |
this.setAttribute("value", value.join(",")); | |
const event = new CustomEvent("change", this.value); | |
this.dispatchEvent(event); | |
} | |
get everythingSelected() { | |
return this.items.length === this.value.length; | |
} | |
onChangeAllCheckbox(evt) { | |
this.value = evt.target.checked ? this.items : []; | |
} | |
onChangeCheckbox(evt) { | |
const oldValues = this.value; | |
if (evt.target.checked) { | |
oldValues.push(evt.target.value); | |
// TODO: remove duplicates | |
} else { | |
const index = oldValues.indexOf(evt.target.value); | |
if (index > -1) { | |
oldValues.splice(index, 1); | |
} | |
} | |
this.value = oldValues; | |
} | |
renderListItem(labelText, value, checked) { | |
const li = document.createElement("li"); | |
const checkedAttribute = checked ? "checked=checked" : ""; | |
const checkbox = document.createElement("input"); | |
checkbox.id = value; | |
checkbox.type = "checkbox"; | |
checkbox.value = value; | |
if (checked) { | |
checkbox.checked = true; | |
} | |
if (value === "all") { | |
checkbox.addEventListener("change", (evt) => | |
this.onChangeAllCheckbox(evt) | |
); | |
} else { | |
checkbox.addEventListener("change", (evt) => this.onChangeCheckbox(evt)); | |
} | |
const label = document.createElement("label"); | |
label.for = value; | |
label.appendChild(checkbox); | |
const textNode = document.createTextNode(labelText); | |
label.appendChild(textNode); | |
li.appendChild(label); | |
return li; | |
} | |
renderList() { | |
const list = document.createElement("ul"); | |
const labels = ["Select All"].concat(this.itemLabels); | |
const values = ["all"].concat(this.items); | |
const checkedItems = this.value; | |
for (let i = 0; i < labels.length; i++) { | |
let isChecked = checkedItems.indexOf(values[i]) > -1; | |
if (values[i] === "all" && this.everythingSelected) { | |
isChecked = true; | |
} | |
list.appendChild(this.renderListItem(labels[i], values[i], isChecked)); | |
} | |
return list; | |
} | |
rerender() { | |
this.container.innerHTML = ""; | |
const title = document.createElement("span"); | |
title.innerText = this.title; | |
this.container.appendChild(title); | |
const list = this.renderList(); | |
this.container.appendChild(list); | |
} | |
connectedCallback() { | |
const shadow = this.attachShadow({ mode: "open" }); | |
shadow.appendChild(this.container); | |
this.rerender(); | |
} | |
attributeChangedCallback(name, oldValue, newValue) { | |
this.rerender(); | |
} | |
} | |
customElements.define("checkbox-list", CheckboxList); |
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