/**
* @file ds-checkbox.js
* @summary A custom Web Component that wraps a native checkbox input element.
* @description
* The `ds-checkbox` component provides a styled and functional checkbox.
* It supports both single checkboxes and groups of checkboxes for multiple selections.
*
* @element ds-checkbox
* @extends HTMLElement
*
* @attr {string} name - The name of the checkbox, used when submitting form data.
* @attr {string} value - The value of the checkbox when checked.
* @attr {boolean} checked - If present, the checkbox is selected.
* @attr {boolean} disabled - If present, the checkbox cannot be interacted with.
* @attr {boolean} readonly - If present, the checkbox cannot be modified by the user.
* @attr {boolean} required - If present, the checkbox must be checked before form submission.
* @attr {string} id - A unique identifier for the checkbox, useful for associating with labels.
*
* @property {boolean} checked - Gets or sets the checked state of the checkbox.
* @property {string} value - Gets or sets the value of the checkbox.
* @property {string} name - Gets or sets the name of the checkbox.
* @property {boolean} disabled - Gets or sets the disabled state of the checkbox.
* @property {boolean} readonly - Gets or sets the readonly state of the checkbox.
* @property {boolean} required - Gets or sets the required state of the checkbox.
*
* @fires change - Fired when the checkbox selection changes.
* @fires focus - Fired when the checkbox receives focus.
* @fires blur - Fired when the checkbox loses focus.
*
* @example
* <!-- Basic checkbox -->
* <ds-checkbox name="agree" value="yes" id="agree-terms">I agree to the terms</ds-checkbox>
*
* @example
* <!-- Checkbox with default selection -->
* <ds-checkbox name="newsletter" value="subscribe" checked>Subscribe to newsletter</ds-checkbox>
*
* @example
* <!-- Multiple checkboxes for preferences -->
* <ds-checkbox name="preferences" value="email">Email notifications</ds-checkbox>
* <ds-checkbox name="preferences" value="sms">SMS notifications</ds-checkbox>
* <ds-checkbox name="preferences" value="push">Push notifications</ds-checkbox>
*/
class DsCheckbox extends HTMLElement {
constructor() {
super();
// Attach shadow root with open mode for experimentation
const shadowRoot = this.attachShadow({ mode: 'open' });
// Define the template with internal markup and styles
const template = document.createElement('template');
template.innerHTML = `
<style>
@import url('/src/design_system/styles.css');
:host {
display: inline-block;
}
.wrapper {
display: flex;
align-items: center;
}
</style>
<div class="wrapper">
<input type="checkbox" id="checkbox" part="checkbox">
<slot></slot>
</div>
`;
// Append the template's content to the shadow root
shadowRoot.appendChild(template.content.cloneNode(true));
// Store reference to the internal checkbox for attribute changes
this.checkbox = shadowRoot.querySelector('input[type="checkbox"]');
// Set up event listeners
this.setupEventListeners();
}
/**
* Defines which attributes the component observes for changes.
* @returns {Array<string>} An array of attribute names to observe.
*/
static get observedAttributes() {
return ['name', 'value', 'checked', 'disabled', 'readonly', 'required', 'id'];
}
/**
* Called when one of the component's observed attributes is added, removed, or changed.
* @param {string} name - The name of the attribute that changed.
* @param {string|null} oldValue - The attribute's old value.
* @param {string|null} newValue - The attribute's new value.
*/
attributeChangedCallback(name, oldValue, newValue) {
if (oldValue === newValue) return; // No change
switch (name) {
case 'name':
this.checkbox.name = newValue || '';
break;
case 'value':
this.checkbox.value = newValue || '';
break;
case 'checked':
if (this.hasAttribute('checked')) {
this.checkbox.checked = true;
} else {
this.checkbox.checked = false;
}
break;
case 'disabled':
if (this.hasAttribute('disabled')) {
this.checkbox.disabled = true;
} else {
this.checkbox.disabled = false;
}
break;
case 'readonly':
if (this.hasAttribute('readonly')) {
this.checkbox.readOnly = true;
} else {
this.checkbox.readOnly = false;
}
break;
case 'required':
if (this.hasAttribute('required')) {
this.checkbox.required = true;
} else {
this.checkbox.required = false;
}
break;
case 'id':
this.checkbox.id = newValue || '';
break;
}
}
/**
* Sets up event listeners to re-dispatch events from the host element.
*/
setupEventListeners() {
const events = ['change', 'focus', 'blur'];
events.forEach(eventType => {
this.checkbox.addEventListener(eventType, (event) => {
// Create a new event to dispatch from the host
const newEvent = new Event(eventType, {
bubbles: true,
composed: true,
cancelable: true
});
// Copy relevant properties
if (eventType === 'change') {
newEvent.target = this;
newEvent.currentTarget = this;
}
this.dispatchEvent(newEvent);
});
});
}
/**
* Gets the checked state of the checkbox.
* @returns {boolean} Whether the checkbox is checked.
*/
get checked() {
return this.checkbox.checked;
}
/**
* Sets the checked state of the checkbox.
* @param {boolean} val - Whether to check the checkbox.
*/
set checked(val) {
this.checkbox.checked = val;
}
/**
* Gets the value of the checkbox.
* @returns {string} The checkbox's value.
*/
get value() {
return this.checkbox.value;
}
/**
* Sets the value of the checkbox.
* @param {string} val - The new value to set.
*/
set value(val) {
this.checkbox.value = val;
}
/**
* Gets the name of the checkbox.
* @returns {string} The checkbox's name.
*/
get name() {
return this.checkbox.name;
}
/**
* Sets the name of the checkbox.
* @param {string} val - The new name to set.
*/
set name(val) {
this.checkbox.name = val;
}
/**
* Gets the disabled state of the checkbox.
* @returns {boolean} Whether the checkbox is disabled.
*/
get disabled() {
return this.checkbox.disabled;
}
/**
* Sets the disabled state of the checkbox.
* @param {boolean} val - Whether to disable the checkbox.
*/
set disabled(val) {
this.checkbox.disabled = val;
}
/**
* Gets the readonly state of the checkbox.
* @returns {boolean} Whether the checkbox is readonly.
*/
get readonly() {
return this.checkbox.readOnly;
}
/**
* Sets the readonly state of the checkbox.
* @param {boolean} val - Whether to make the checkbox readonly.
*/
set readonly(val) {
this.checkbox.readOnly = val;
}
/**
* Gets the required state of the checkbox.
* @returns {boolean} Whether the checkbox is required.
*/
get required() {
return this.checkbox.required;
}
/**
* Sets the required state of the checkbox.
* @param {boolean} val - Whether to make the checkbox required.
*/
set required(val) {
this.checkbox.required = val;
}
/**
* Called when the element is connected to the DOM.
* Applies initial attributes.
*/
connectedCallback() {
// Apply initial attributes
this.attributeChangedCallback('name', null, this.getAttribute('name'));
this.attributeChangedCallback('value', null, this.getAttribute('value'));
this.attributeChangedCallback('checked', null, this.getAttribute('checked'));
this.attributeChangedCallback('disabled', null, this.getAttribute('disabled'));
this.attributeChangedCallback('readonly', null, this.getAttribute('readonly'));
this.attributeChangedCallback('required', null, this.getAttribute('required'));
this.attributeChangedCallback('id', null, this.getAttribute('id'));
}
}
// Register the custom element
customElements.define('ds-checkbox', DsCheckbox);