kazu69 · February 25, 2018 10:39 · kazu69 · Feb 25, 2018
diff --git a/web_component.html b/web_component.html
 <!DOCTYPE html>
 <html lang="en">
 <head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>

    <style>
        custom-checkbox {
          vertical-align: middle;
        }
        howto-label {
          vertical-align: middle;
          display: inline-block;
          font-weight: bold;
          font-family: sans-serif;
          font-size: 20px;
          margin-left: 8px;
        }
      </style>
 </head>
 <body>
        <custom-checkbox id="join-checkbox"></custom-checkbox>
        <custom-label for="join-checkbox">Join Newsletter</custom-label>
 <script>
    (function() {

        class CustomCheckbox extends HTMLElement {
            // obsering attributes change
            // https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements#Observed_attributes
            static get observedAttributes() {
                return ['checked', 'disabled']
            }

            constructor(args) {
                super(args)

                this.KEYCODE = {
                    SPACE: 32
                }

                // set initial props
                this.checked = false
                this.disabled = false

                // attach shadowDOM 
                // https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_shadow_DOM
                // https://developer.mozilla.org/en-US/docs/Web/API/Element/attachShadow
                const shadowRoot = this.attachShadow({mode: 'open'})

                // create <template> tag
                const template = document.createElement('temaplte')
                template.innerHTML = this.context
                this.shadowRoot.appendChild(template)
            }

            // set custom element callbacks
            // https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements#Custom_element_methods
            connectedCallback() {
                console.log(`HowToCheckbox inserted to document`)

                // set role
                if (!this.hasAttribute('role')) {
                    this.setAttribute('role', 'checkbox');
                }

                // set tabindex
                if (!this.hasAttribute('tabindex')) {
                    this.setAttribute('tabindex', 0);
                }

                // add eventListner
                this.addEventListener('keyup', this._onKeyUp)
                this.addEventListener('click', this._onClick)
            }

            get context() {
                // https://developer.mozilla.org/en-US/docs/Web/CSS/:host
                return `
                    <style>
                        :host {
                          box-sizing: border-box;
                          display: inline-block;
                          background-color: #efefef;
                          border: 1px solid #ddd;
                          width: 16px;
                          height: 16px;
                        }
                        :host([hidden]) {
                          display: none;
                        }
                        :host([checked]) {
                            background-color: #000;
                        }
                        :host([disabled]) {
                          background-color: #fff;
                        }
                        :host([checked][disabled]) {
                            background-color: #fff;
                        }
                      </style>
                `
            }

            set checked(value) {
                const isChecked = Boolean(value);
                if (isChecked) {
                    this.setAttribute('checked', '')
                } else {
                    this.removeAttribute('checked')
                }
            }

            get checked() {
                return this.hasAttribute('checked');
            }

            set disabled(value) {
                const isDisabled = Boolean(value);
                if (isDisabled) {
                    this.setAttribute('disabled', '')
                } else {
                    this.removeAttribute('disabled')
                }
            }

            get disabled() {
                return this.hasAttribute('disabled');
            }

            _onKeyUp(event) {
                switch (event.keyCode) {
                    case this.KEYCODE.SPACE:
                        event.preventDefault();
                        this._toggleChecked();
                        break
                    default:
                        return
                }
            }

            _onClick(event) {
                this._toggleChecked()
            }

            _toggleChecked() {
                if (this.disabled) {
                    return
                }
                this.checked = !this.checked

                // dispatch change event
                // https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent
                // https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent
                const changeEvent = new CustomEvent({
                    detail: {
                        checked: this.checked,
                    },
                    bubbles: true,
                })
                this.dispatchEvent(changeEvent)
            }

            disconnectedCallback() {
                console.log(`HowToCheckbox deleted from document`)
                this.removeEventListener('keyup', this._onKeyUp)
                this.removeEventListener('click', this._onClick)
            }

            attributeChangedCallback(attributeName, oldValue, newValue) {                
                console.log(`HowToCheckbox attributes changed`)
                const hasValue = newValue !== null
                switch(attributeName) {
                    case 'checked':
                        this.setAttribute('aria-checked', hasValue)
                        break
                    case 'disabled':
                        this.setAttribute('aria-disabled', hasValue)

                        if (hasValue) {
                            this.removeAttribute('tabindex')
                            this.blur()
                        } else {
                            this.setAttribute('tabindex', '0')
                        }

                        break
                }
            }

            adoptedCallback() {
                console.log(`HowToCheckbox adopted from document`)
            }

        }

        // https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements
        // https://developer.mozilla.org/ja/docs/Web/API/CustomElementRegistry/define
        window.customElements.define('custom-checkbox', CustomCheckbox);



        class CustomLabel extends HTMLElement {
            constructor() {
                super()

                const shadowRoot = this.attachShadow({mode: 'open'})
                const template = document.createElement('temaplte')
                template.innerHTML = this.context
                this.shadowRoot.appendChild(template)

                this.addEventListener('click', this._onClick);
            }

            static get observedAttributes() {
                return ['for']
            }

            _onClick(event) {
                let el = this._currentLabelTarget();          
                if (!el || event.target === el) {
                  return;
                }
                el.focus();
                el.click();
              }

              _currentLabelTarget() {
                  let scope = this.getRootNode();
                  return scope.getElementById(this.for)
              }

            connectedCallback() {

            }

            get for() {
                const value = this.getAttribute('for');
                return value === null ? '' : value;
            }

            set for(value) {
                this.setAttribute('for', value);
            }
         
            get context() {
                // <slot> tag https://developer.mozilla.org/en-US/docs/Web/HTML/Element/slot
                return `
                <style>
                    :host {
                        cursor: pointer;
                    }
                </style>
                <slot></slot>
                `;
            }
        }

        window.customElements.define('custom-label', CustomLabel);
    })();
 </script>
 <ul>
    <li>https://developers.google.com/web/fundamentals/web-components/shadowdom</li>
 </ul>
 </body>
 </html>
	<!DOCTYPE html>
	<html lang="en">
	<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Document</title>

	<style>
	custom-checkbox {
	vertical-align: middle;
	}
	howto-label {
	vertical-align: middle;
	display: inline-block;
	font-weight: bold;
	font-family: sans-serif;
	font-size: 20px;
	margin-left: 8px;
	}
	</style>
	</head>
	<body>
	<custom-checkbox id="join-checkbox"></custom-checkbox>
	<custom-label for="join-checkbox">Join Newsletter</custom-label>
	<script>
	(function() {

	class CustomCheckbox extends HTMLElement {
	// obsering attributes change
	// https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements#Observed_attributes
	static get observedAttributes() {
	return ['checked', 'disabled']
	}

	constructor(args) {
	super(args)

	this.KEYCODE = {
	SPACE: 32
	}

	// set initial props
	this.checked = false
	this.disabled = false

	// attach shadowDOM
	// https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_shadow_DOM
	// https://developer.mozilla.org/en-US/docs/Web/API/Element/attachShadow
	const shadowRoot = this.attachShadow({mode: 'open'})

	// create <template> tag
	const template = document.createElement('temaplte')
	template.innerHTML = this.context
	this.shadowRoot.appendChild(template)
	}

	// set custom element callbacks
	// https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements#Custom_element_methods
	connectedCallback() {
	console.log(`HowToCheckbox inserted to document`)

	// set role
	if (!this.hasAttribute('role')) {
	this.setAttribute('role', 'checkbox');
	}

	// set tabindex
	if (!this.hasAttribute('tabindex')) {
	this.setAttribute('tabindex', 0);
	}

	// add eventListner
	this.addEventListener('keyup', this._onKeyUp)
	this.addEventListener('click', this._onClick)
	}

	get context() {
	// https://developer.mozilla.org/en-US/docs/Web/CSS/:host
	return `
	<style>
	:host {
	box-sizing: border-box;
	display: inline-block;
	background-color: #efefef;
	border: 1px solid #ddd;
	width: 16px;
	height: 16px;
	}
	:host([hidden]) {
	display: none;
	}
	:host([checked]) {
	background-color: #000;
	}
	:host([disabled]) {
	background-color: #fff;
	}
	:host([checked][disabled]) {
	background-color: #fff;
	}
	</style>
	`
	}

	set checked(value) {
	const isChecked = Boolean(value);
	if (isChecked) {
	this.setAttribute('checked', '')
	} else {
	this.removeAttribute('checked')
	}
	}

	get checked() {
	return this.hasAttribute('checked');
	}

	set disabled(value) {
	const isDisabled = Boolean(value);
	if (isDisabled) {
	this.setAttribute('disabled', '')
	} else {
	this.removeAttribute('disabled')
	}
	}

	get disabled() {
	return this.hasAttribute('disabled');
	}

	_onKeyUp(event) {
	switch (event.keyCode) {
	case this.KEYCODE.SPACE:
	event.preventDefault();
	this._toggleChecked();
	break
	default:
	return
	}
	}

	_onClick(event) {
	this._toggleChecked()
	}

	_toggleChecked() {
	if (this.disabled) {
	return
	}
	this.checked = !this.checked

	// dispatch change event
	// https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent
	// https://developer.mozilla.org/en-US/docs/Web/API/CustomEvent/CustomEvent
	const changeEvent = new CustomEvent({
	detail: {
	checked: this.checked,
	},
	bubbles: true,
	})
	this.dispatchEvent(changeEvent)
	}

	disconnectedCallback() {
	console.log(`HowToCheckbox deleted from document`)
	this.removeEventListener('keyup', this._onKeyUp)
	this.removeEventListener('click', this._onClick)
	}

	attributeChangedCallback(attributeName, oldValue, newValue) {
	console.log(`HowToCheckbox attributes changed`)
	const hasValue = newValue !== null
	switch(attributeName) {
	case 'checked':
	this.setAttribute('aria-checked', hasValue)
	break
	case 'disabled':
	this.setAttribute('aria-disabled', hasValue)

	if (hasValue) {
	this.removeAttribute('tabindex')
	this.blur()
	} else {
	this.setAttribute('tabindex', '0')
	}

	break
	}
	}

	adoptedCallback() {
	console.log(`HowToCheckbox adopted from document`)
	}

	}

	// https://developer.mozilla.org/ja/docs/Web/Web_Components/Custom_Elements
	// https://developer.mozilla.org/ja/docs/Web/API/CustomElementRegistry/define
	window.customElements.define('custom-checkbox', CustomCheckbox);



	class CustomLabel extends HTMLElement {
	constructor() {
	super()

	const shadowRoot = this.attachShadow({mode: 'open'})
	const template = document.createElement('temaplte')
	template.innerHTML = this.context
	this.shadowRoot.appendChild(template)

	this.addEventListener('click', this._onClick);
	}

	static get observedAttributes() {
	return ['for']
	}

	_onClick(event) {
	let el = this._currentLabelTarget();
	if (!el \|\| event.target === el) {
	return;
	}
	el.focus();
	el.click();
	}

	_currentLabelTarget() {
	let scope = this.getRootNode();
	return scope.getElementById(this.for)
	}

	connectedCallback() {

	}

	get for() {
	const value = this.getAttribute('for');
	return value === null ? '' : value;
	}

	set for(value) {
	this.setAttribute('for', value);
	}

	get context() {
	// <slot> tag https://developer.mozilla.org/en-US/docs/Web/HTML/Element/slot
	return `
	<style>
	:host {
	cursor: pointer;
	}
	</style>
	<slot></slot>
	`;
	}
	}

	window.customElements.define('custom-label', CustomLabel);
	})();
	</script>
	<ul>
	<li>https://developers.google.com/web/fundamentals/web-components/shadowdom</li>
	</ul>
	</body>
	</html>