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HTML

              
                # Auto Resize a `<textarea>` with a Web Component

**There’s another way to do this: extend custom elements! [See this codepend](https://codepen.io/jimniels/pen/MWeawPV).**

First, a regular `<textarea>`.

<textarea>Will NOT auto resize.</textarea>

Now a web component that wraps a `<textarea>` so that it auto resizes on input.

<textarea-autosize>
  <textarea>Will auto resize.</textarea>
</textarea-autosize>

Leveraging a `<textarea>` as a child means things fail gracefully if JavaScript isn’t present. Plus, you can still use the inner `<textarea>` to attach any attributes that are supported natively in HTML.

<textarea-autosize>
  <textarea rows="5" onclick="console.log('this fired')">Default value here with the attribute `rows="5" and an `onclick` event handler.</textarea>
</textarea-autosize>

What if you don’t add a child `<textarea>` to the web component? It won’t work. Note that nothing displays under here.

<textarea-autosize></textarea-autosize>
              
            
!

CSS

              
                textarea {
  display: block;
  margin: 20px 0;
  width: 400px;
}
              
            
!

JS

              
                import autosize from "https://unpkg.com/autosize@4.0.2/src/autosize.js";

class TextareaAutosize extends HTMLElement {
  connectedCallback() {
    let textarea = this.querySelector("textarea");
    if (textarea) {
      autosize(textarea);
    } else {
      console.error("<textarea-autosize> requires a child <textarea>.");
    }
  }
}
    
customElements.define('textarea-autosize', TextareaAutosize);
              
            
!
999px

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