Create native Web Components with Shadow DOM, custom elements, and slots with live preview.
Custom elements, shadow DOM, and slots each carry their own small, easy-to-fumble API, and this tool wires the three together into one working component class as you fill in a tag name, attributes, and a list of slots, updating a live preview pane so you can see the rendered element immediately rather than guessing from source. The detail that catches people most often: a custom element tag name must contain a hyphen, per the Custom Elements specification, so the browser can tell it apart from any future built-in HTML tag. A single-word name like "card" is invalid and will not register.
You enter a tag name, and the tool scaffolds a JavaScript class extending HTMLElement, wiring lifecycle stubs such as connectedCallback, and registers it with customElements.define(tagName, class). Because the Custom Elements spec requires autonomous element names to contain a hyphen (a lowercase, ASCII compound word), a name submitted without one is invalid, and the tool should flag it before generating a tag the browser would refuse to register.
The generator attaches a shadow root to the element and inserts slot elements for each placeholder you define, named or default, then renders the assembled markup in a live preview so you can see how content projected into the light DOM fills each slot, and how styles scoped inside the shadow root stay isolated from the rest of the page, without opening a separate browser tab to check.
No. The output is a vanilla Custom Elements v1 class using the standard browser API (HTMLElement, attachShadow, customElements.define), so it runs in any framework or in none at all, though you still need to import or paste the script before the tag is used on a page.
No. Native custom elements and shadow DOM are not supported in IE11, and the tool does not generate polyfills. For legacy browser support you would need to add the webcomponents.js polyfill suite yourself and test it separately.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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