Detect if Element is a Web Component

By  on  

I've advocated for web components since before they became a spec, mostly inspired by the Dojo Toolkit's dijit framework. Empowering first class JavaScript widgets, as opposed to a mess of DIVs and templates, always made the most sense. Now that web components exist, and awesome frameworks like Ionic are based on them, I wanted to discover how to detect a web component, as opposed to a regular HTML element, with JavaScript. As it turns out, it's much easier than you'd think.

Assuming you have a reference to an element, it's as easy as detecting a dash in the element's tag:

function isWebComponent(element) {
  return element.tagName.includes("-");
}

The web component spec requires a dash in the HTMLElement's tagName, so detecting a web component is essentially nailed down to a string comparison.

If you haven't played with web components, I really hope you find the time. Having lived through decades of "widgets" and over-nesting of arbitrary DIVs and unreadable code, I've learned to appreciate these gems!

Recent Features

  • By
    Interview with a Pornhub Web Developer

    Regardless of your stance on pornography, it would be impossible to deny the massive impact the adult website industry has had on pushing the web forward. From pushing the browser's video limits to pushing ads through WebSocket so ad blockers don't detect them, you have...

  • By
    How I Stopped WordPress Comment Spam

    I love almost every part of being a tech blogger:  learning, preaching, bantering, researching.  The one part about blogging that I absolutely loathe:  dealing with SPAM comments.  For the past two years, my blog has registered 8,000+ SPAM comments per day.  PER DAY.  Bloating my database...

Incredible Demos

  • By
    Do / Undo Functionality with MooTools

    We all know that do/undo functionality is a God send for word processing apps. I've used those terms so often that I think of JavaScript actions in terms of "do" an "undo." I've put together a proof of concept Do/Undo class with MooTools. The MooTools...

  • By
    LightFace:  Facebook Lightbox for MooTools

    One of the web components I've always loved has been Facebook's modal dialog.  This "lightbox" isn't like others:  no dark overlay, no obnoxious animating to size, and it doesn't try to do "too much."  With Facebook's dialog in mind, I've created LightFace:  a Facebook lightbox...

Discussion

  1. Wouldn’t that just check whether it is a custom element? To my knowledge, custom elements can live on their own and do not have to be actual web components.

    • Šime Vidas

      Could you explain the difference between a custom element and a web component?

    • Jv

      My exact thought, Catalin! This isn’t really robust enough..

  2. Yaisiel

    I feel like that will not work if you declare your web component as a “customized built-in” (https://developer.mozilla.org/en-US/docs/Web/Web_Components/Using_custom_elements#Customized_built-in_elements). That type of component is built on top of an existing element (like a for example) and the tag names don’t contain hyphens. I’m not sure, however, how many people would follow that approach in practice. It might be that, for the majority of the cases, checking for hyphens is enough.

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!