teChangedCallback() { <span class="hljs-keyword">this</span>.setTextContent(); }
        <span class="hljs-keyword">static</span> get observedAttributes() { <span class="hljs-keyword">return</span> [<span class="hljs-string">&apos;lang&apos;</span>,<span class="hljs-string">&apos;year&apos;</span>,<span class="hljs-string">&apos;month&apos;</span>]; }

        <span class="hljs-comment">// &#x5C5E;&#x6027;&#x306E;&#x5024;&#x3092;&#x4F7F;&#x3063;&#x3066;`textContent`&#x3092;&#x66F4;&#x65B0;&#x3057;&#x307E;&#