Question 1

How to polyfill custom elements builtin extends in my project?

Accepted Answer

Include this polyfill script before your custom elements code, but note it's deprecated; for current projects, use @ungap/custom-elements instead to ensure compatibility and support.

Question 2

Is builtin extends polyfill still needed with Chrome or Firefox?

Accepted Answer

Check specific browser versions; most modern browsers now support builtin extends natively, but this polyfill is useful for older versions or edge cases where support is lacking.

Question 3

Custom elements builtin vs @ungap/custom-elements: which should I use?

Accepted Answer

Use @ungap/custom-elements for new projects, as it's the actively maintained successor with full feature detection, while custom-elements-builtin is deprecated and limited in scope.

Question 4

Can I use this with React or Vue for web components?

Accepted Answer

Yes, it's a low-level polyfill that works with any framework using custom elements, but integration might require careful setup to avoid conflicts with framework-specific rendering.

Question 5

What happens if I don't polyfill builtin extends?

Accepted Answer

Custom elements extending native elements may fail in unsupported browsers, breaking functionality and accessibility, so testing across target browsers is crucial.

Question 6

How to migrate from custom-elements-builtin to the new polyfill?

Accepted Answer

Replace the script import with @ungap/custom-elements and update your code, as the new polyfill might have different initialization or API methods for broader support.

@ungap/custom-elements-builtin

What is @ungap/custom-elements-builtin?

Overview

Use Cases

Best For

Found a gem we're missing?

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions