title: this.shadowRoot.getElementById(...).textContent is not a function
body: <p>Hello i'm trying to create my first custom component</p>
  <p>This is my template</p>
  <pre><code>     &lt;div class=&quot;wrap-boxo&quot;&gt;
    &lt;div class=&quot;boxo&quot;&gt;
      &lt;div class=&quot;top-boxo&quot;&gt;
        &lt;div class=&quot;pal focussed&quot;&gt;&lt;/div&gt;
        &lt;div class=&quot;pal&quot;&gt;&lt;/div&gt;  
      &lt;/div&gt;
    &lt;div class=&quot;message&quot;&gt;
      &lt;div class=&quot;left-boxo&quot;&gt;
  
      &lt;div class=&quot;icon&quot;&gt;
        &lt;div class=&quot;ico&quot;&gt;&lt;/div&gt;
        &lt;div class=&quot;shd&quot;&gt;&lt;/div&gt;
  
      &lt;/div&gt;
  
      &lt;div class=&quot;type-mex&quot;&gt;
        &lt;h3 id=&quot;dd&quot; class=&quot;main-type&quot;&gt;&lt;/h3&gt;
        &lt;p class=&quot;main-det&quot;&gt;&lt;/p&gt;
      &lt;/div&gt;
  
      &lt;button&gt; &lt;h3 class=&quot;col-txt&quot;&gt; &lt;/h3&gt; &lt;/button&gt;
  
    &lt;/div&gt;
    &lt;div class=&quot;right-boxo&quot;&gt;
      &lt;p&gt;&lt;/p&gt;
  
    &lt;/div&gt;
    &lt;/div&gt;
  
    &lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  <p>in the connectedCallback() i do my settings</p>
  <pre><code>connectedCallback(){
  
        let tipo_boxo = this.getAttribute(&quot;type&quot;);
        this.shadowRoot.querySelector(&quot;.boxo&quot;).classList.add(type_boxo);
        let image = this.getAttribute(&quot;iconimg&quot;);
        this.shadowRoot.querySelector('.ico').style.backgroundImage= &quot;url(&quot;+image+&quot;)&quot;;
        let main_type = this.getAttribute(&quot;main-type&quot;);
        this.shadowRoot.querySelector(&quot;.main-type&quot;).classList.add(main_type);
        this.shadowRoot.getElementById(&quot;dd&quot;).textContent(&quot;Error&quot;)
         
  
          }
  </code></pre>
  <p>it worked just fine until i tried to add a textcontent in the h3  the
  <code>this.shadowRoot.getElementById(&quot;dd&quot;).textContent(&quot;Error&quot;)</code> generate an error</p>
  <pre><code>Uncaught TypeError: this.shadowRoot.getElementById(...).textContent is not a function
      at HTMLElement.connectedCallback (home.html:897) 
  </code></pre>
  <p>what am i doing wrong?</p>
  <p>this is my custom element if i do a console log of
  this.shadowRoot.getElementById(&quot;dd&quot;) i get it in the console but as soon as i do textContent or innerHTML i get this error</p>
  <pre><code>&lt;bo-xo 
    mex=&quot;error&quot;
    tipo=&quot;success&quot; 
    main-type=&quot;errh3&quot;
    iconimg=&quot;some-img.jpg&quot;&gt;
  &lt;/bo-xo&gt;
  </code></pre>