Copyright表示の年号部分をアクセスした年に応じて調整してくれるだけのWeb Components

pandanote-copyright.js

class CopyrightLinkElement extends HTMLElement {
	static get observedAttributes() {
		return ['established'];
	}
	constructor() {
		super();
	}

	connectedCallback() {
	}

	attributeChangedCallback(name, oldValue, newValue) {
		var established = newValue;
		if (established == null || established == "" || /[^\d]/.test(established)) {
			established = 2020;
		}
		var now = new Date();
		var year = now.getFullYear();
		var yearspan = "";
		if (year <= established) {
			yearspan = year;
		} else {
			yearspan = established+"-"+year;
		}
		this.innerHTML = 'Copyright '+yearspan+' by <a href="https://pandanote.info/">pandanote.info</a>';
	}
}

customElements.define("pandanote-copyright",CopyrightLinkElement);